Here is a sample of data am working at, which consists of two columns V1 and V2 

```
         V1        V2
1   A415Z A415Z   1.010
2   A415J A415Z   0.960
3   B416X A415Z   0.980
4   B416Z A415Z   0.990
5   B416J A415Z   1.020
6   B416M A415Z   1.085
7   B416P A415Z   6.380
8   B416W A415Z   0.995
9   D420R A415Z   0.995
10  D420H A415Z   0.975
11  B416X B416X   0.950
12  B416Z B416X   0.960
13  B416J B416X   0.990
14  B416M B416X   1.055

```

In the first column "V1" , I want to remove the rows which have the two words start with the same character.
For example : In the first , second and last four rows the elements are: A415Z A415Z, A415J A415Z, B416X B416X, 
B416Z B416X , B416J B416X, B416M B416X. so the output should look like the one given below. 

```
         V1         V2
1   B416X A415Z   0.980
2   B416Z A415Z   0.990
3   B416J A415Z   1.020
4   B416M A415Z   1.085
5   B416P A415Z   6.380
6   B416W A415Z   0.995
7   D420R A415Z   0.995
8   D420H A415Z   0.975

```

How can I make use of a regular expressions here? (or) if there is better method suggestions will be helpful.