A couple of points to add.
One way to look at the calipers with 2 bleeder screws is; What are you trying to do?
If you are trying to get all the air out of the system, use the top bleeder as air bubbles rise.
If you want to get the gunk out of the caliper, bleed on both, with the bottom one first.
Also, there is a very interesting reaction that some MC rubber seals have with DOT4 brake fluid. I found this out on my 993, but it goes for other cars as well. The PO had DOT4 in the 993 and didn't change it often (ever?), which hardened the rubber bits in the MC and cause a slightly sinking pedal.
The shop that I use identified that if I were to use DOT 3 for a while until the pedal stiffened, then switch back to DOT4, and then regularly flush the DOT4 I should be golden (and not replace a $900 MC).
I was highly skeptical, but went though with the $150 flush.
Amazingly it worked perfectly
So know that DOT3 and DOT4 does affect rubber seals differently.