Don't have any knowledge of Shimano and I am hoping the answer to this is straightforward without a lot of exceptions and what ifs. I am wondering if the same Shimano shifters can be used on both a double and triple setup, like Campy? Or does Shimano have separate shifters dedicated to double and triple configurations? If the answer to this is group and vintage dependent, then assume I am talking about Simano 600 tri color or Shimano 6503 Ultegra. Thanks!

for brifters, they are speed specific. You can run a triple shifter on a double, but not vice versa.

Shimano does make shifters for doubles and shifters for triples. I pretty sure the last digit 3 in the 6503 would designate a triple. You can set up a triple shifter to work with a double, but I think you may lose some of the trimability on the "middle", now inner, ring when you do this.

+1.

Down tube shifters can be used on doubles or triples. 3s STI levers can be used on either as well.

I think the 5500/6500 series STI's were dfouble/triple specific, but Shimano actually marketed 5600/6600 STI's as suitable for doubles or triples for at least a year. Bought a bunch of them over time and set them up on doubles per the instructions where the small and big rings were treated as the small and middle rings on a triple, leaving a 'vacant' unused option locked out by the limiting screw on the FD. After awhile -even though the writing on the box didn't change- I started seeing a little tag affixed to each STI indicating that the STI would break if 'overupshifted' beyond the big ring and the warranty would not cover damage caused by doing so. NBD, I thought- they could also be set up for a double by treating the rings the same as the big and middle on a triple, that way the only thing a rider could do was 'overdownshift' and put more slack in the cable. The the last set I received had a tag on the inside saying that they were unsuitable for double chainring setups. So, go figure.

I know the Ultegra ST-6510 brifters are compatible with both double and triple cranks.

I'm going to do this the next time I install mine. Setting them up for "small and middle" is tricky and it is easy to get the shifter to bind. I did it a few times when I didnt know any better, luckily I didn't break them when I forced it shift back down.