My close grip bench is stronger than normal/wide grip

I realised recently that I can bench press at least the same, but probably more, using a close grip. Is this normal?

I use fairly standard grip widths. For my normal bench I hold my ring finger on the ring of the barbell, and close grip I have my index finger just on the knurling. I'm 6'5 so it's not like I'm using an abnormally wide grip for my body type.

Can you think of any possible reasons for this? And is it something I actually need to work on and correct or should I just move forward using a narrower grip?