Thank you very much, perf12.
3c and 15c: You've found nearly equally toned/stained/damaged stamps and that's that.
Impression sur raccord: This means printed on paper showing a repair with a splice/patch. See:https://www.ffap.net/Philatelie/lex...phil.php?l=I
You're going off the rails here. No such thing is listed for 117 which you are showing here.