It depends. I have had 2 back to back babies, weighing within half an ounce of each other.
Ds1 (my first labour) ended up being a forceps delivery after my labour was induced after my waters broke but labour failed to start. He was stuck, going nowhere after 2 hours of pushing, and he was becoming distressed.
Ds3 (my fourth labour) was a straightforward, spontaneous labour. He took a little longer than expected to be pushed out (but we are talking minutes here, not hours) and when he was born, the MW was surprised to find out he was back to back and said "oh that is why he took a bit longer to come".
For ds1 I had pethidine and G&A and only didn't have an epidural because the hospital did not do them except for planned CS. I certainly wish I had had an epidural. For ds3, I had nothing but G&A.
So,in my mind, birthing ds3 was not an especially heroic feat for me, but getting ds1 out without an epidural was! The mw explained to me that if a first labour is back to back, the mother's body can struggle, but subsequent back to back labours tend to be easier as the mother's body knows what to do.