The absorption may or may have not been affected today, but I took another pill from a spare pack just in case. If I didn’t need it would this compromise the effectiveness of the pill?

No

It just may increase side effects

Thank you. I’m mostly just concerned about effectiveness :) if it was the 4th to last active pill that I doubled up on, could I still take the 7 break week pills as normal?

As long as you have 7 pills in a row before your break you can take your break week

No I’ve always kept an extra BC pack in case I drop one, throw up one, etc