I was playing white and I had one pawn at a7 and the other at a6. My opponent didn't let me promote the pawn to a Queen stating that when two pawns are in the same column then the pawn doesn't get promoted.

Is this correct? If so, then what happens to a pawn which reaches a8? Does that become useless?

![enter image description here](https://i.stack.imgur.com/Xrb6H.jpg)