I have this problem after I merged/combined multiple columns: 

```
df = 
Name    id  id_x    id_y    age age_x
A   111 111     20  
B   112     112     30
C       113 113 40  40

```

My goal is to clean them up like this:

```
Name    id  age
A   111 20
B   112 30
C   113 40

```

Thank you in advance!