Let's start with this dataset:

```
structure(list(Etiqueta = structure(c(17L, 19L, 4L, 26L, 25L, 
11L, 23L, 5L, 10L, 8L, 13L, 15L, 12L, 9L, 14L, 18L, 1L, 19L, 
4L, 26L), .Label = c("70th Anniversary of First Soviet Stamp", 
"Biathlon", "Buy Now:", "Catalog codes:", "Colors:", "Cross-country skiing", 
"Description:", "Emission:", "Face value:", "Format:", "Issued on:", 
"Paper:", "Perforation:", "Print run:", "Printing:", "Related items:", 
"Sable (Martes zibellina), Cedar", "Score:", "Series:", "Sheet of 8 x SU5789", 
"Sheet of 8 x SU5790", "Similar:", "Size:", "Slalom", "Themes:", 
"Variants:", "XV Winter Olympic Games in Calgary."), class = "factor"), 
    Valor = structure(c(72L, 52L, 54L, 44L, 38L, 11L, 15L, 43L, 
    78L, 51L, 47L, 66L, 70L, 20L, 23L, 28L, 32L, 32L, 55L, 44L
    ), .Label = c("", "1 (See)", "10 Russian kopek", "11%\tAccuracy: Very High", 
    "13%\tAccuracy: Very High", "15 Russian kopek", "15,000", 
    "15%\tAccuracy: Very High", "18%\tAccuracy: Very High", "1988-01-04", 
    "1988-03", "20 Russian kopek", "22%\tAccuracy: Very High", 
    "23%\tAccuracy: Very High", "26 x 37 mm", "28 x 40 mm", "3 sale offers from US$ 0.09", 
    "3,000,000", "3,320,000", "35 Russian kopek", "4 sale offers from US$ 0.09", 
    "4 sale offers from US$ 0.20", "4,000,000", "4,120,000", 
    "40 Russian kopek", "5 Russian kopek", "5,320,000", "53%\tAccuracy: Medium", 
    "56 x 40 mm", "6 sale offers from US$ 0.21", "7 sale offers from US$ 0.07", 
    "70th Anniversary of First Soviet Stamp", "8 sale offers from US$ 0.05", 
    "8*15 Russian kopek", "80%\tAccuracy: Medium", "81%\tAccuracy: Medium", 
    "83%\tAccuracy: Medium", "Animals (Fauna) | Mammals", "Anniversaries and Jubilees | Hands | Stamps", 
    "Biathlon", "Biathlon | Olympic Games | Sports", "Biathlon | Olympic Games | Sports | Winter Sports", 
    "Brown black", "Click to see variants", "coated", "comb 11½", 
    "comb 12½ x 12", "Commemorative", "Cross-country skiing", 
    "Cross-country Skiing | Olympic Games | Sports | Winter Sports", 
    "Definitive", "Definitive Issue No.12", "frame 11½", "Mi:SU 5427AwI", 
    "Mi:SU 5786-5787, Sn:SU 5626A, Yt:SU 5472-5473, Sg:SU 5836-5837, AFA:SU 5726-27", 
    "Mi:SU 5786, Sn:SU 5625, Yt:SU 5472, Sg:SU 5836, AFA:SU 5726", 
    "Mi:SU 5787, Sn:SU 5626, Yt:SU 5473, Sg:SU 5837, AFA:SU 5727", 
    "Mi:SU 5788, Sn:SU 5627, Yt:SU 5474, Sg:SU 5830", "Mi:SU 5788KB", 
    "Mi:SU 5789, Sn:SU 5628, Yt:SU 5475, Sg:SU 5831", "Mi:SU 5789KB", 
    "Mi:SU 5790, Yt:SU 5476, Sg:SU 5832", "Mi:SU 5790KB", "Mini Sheet", 
    "Multicolor", "Offset lithography", "Olympic Games | Skiing | Slalom | Sports | Winter Sports", 
    "Olympic Games | Skiing | Sports", "Olympic Games | Slalom | Sports | Winter Sports", 
    "ordinary", "Photogravure", "Sable (Martes zibellina), Cedar", 
    "Se-tenant", "Severing the chain of bondage", "Sheet of 8 x SU5789", 
    "Sheet of 8 x SU5790", "Slalom", "Stamp", "Winter Olympic Games 1988, Calgary", 
    "XV Winter Olympic Games in Calgary."), class = "factor")), .Names = c("Etiqueta", 
"Valor"), row.names = c(NA, 20L), class = "data.frame")

```

As you can see, it is a data frame with 2 columns and 20 rows. This is the data frame:

```
                                 Etiqueta                                                                          Valor
1         Sable (Martes zibellina), Cedar                                                Sable (Martes zibellina), Cedar
2                                 Series:                                                         Definitive Issue No.12
3                          Catalog codes:                                                                  Mi:SU 5427AwI
4                               Variants:                                                          Click to see variants
5                                 Themes:                                                      Animals (Fauna) | Mammals
6                              Issued on:                                                                        1988-03
7                                   Size:                                                                     26 x 37 mm
8                                 Colors:                                                                    Brown black
9                                 Format:                                                                          Stamp
10                              Emission:                                                                     Definitive
11                           Perforation:                                                                  comb 12½ x 12
12                              Printing:                                                             Offset lithography
13                                 Paper:                                                                       ordinary
14                            Face value:                                                               35 Russian kopek
15                             Print run:                                                                      4,000,000
16                                 Score:                                                          53%\tAccuracy: Medium
17 70th Anniversary of First Soviet Stamp                                         70th Anniversary of First Soviet Stamp
18                                Series:                                         70th Anniversary of First Soviet Stamp
19                         Catalog codes: Mi:SU 5786-5787, Sn:SU 5626A, Yt:SU 5472-5473, Sg:SU 5836-5837, AFA:SU 5726-27
20                              Variants:                                                          Click to see variants

```

By looking atthe table, you can see that rows 1 and 17 contain the same value in both columns, so that their values are repeated. In these cases, I would like to convert the value of the left column in `Title`.

Notice this is an example, and I could do it manually. However, the original dataframe is significantly larger.

So, how can I convert left column name in title in those repeated values in the rows? The resulting data frame migh be identical to the next one:

```
                                 Etiqueta                                                                          Valor
1                                   Title                                                Sable (Martes zibellina), Cedar
2                                 Series:                                                         Definitive Issue No.12
3                          Catalog codes:                                                                  Mi:SU 5427AwI
4                               Variants:                                                          Click to see variants
5                                 Themes:                                                      Animals (Fauna) | Mammals
6                              Issued on:                                                                        1988-03
7                                   Size:                                                                     26 x 37 mm
8                                 Colors:                                                                    Brown black
9                                 Format:                                                                          Stamp
10                              Emission:                                                                     Definitive
11                           Perforation:                                                                  comb 12½ x 12
12                              Printing:                                                             Offset lithography
13                                 Paper:                                                                       ordinary
14                            Face value:                                                               35 Russian kopek
15                             Print run:                                                                      4,000,000
16                                 Score:                                                          53%\tAccuracy: Medium
17                                  Title                                         70th Anniversary of First Soviet Stamp
18                                Series:                                         70th Anniversary of First Soviet Stamp
19                         Catalog codes: Mi:SU 5786-5787, Sn:SU 5626A, Yt:SU 5472-5473, Sg:SU 5836-5837, AFA:SU 5726-27
20                              Variants:                                                          Click to see variants

```