I am certainly not an expert on the issue, but I would say that what counts is what is written on the ticket (PC or 20/30/40)

I just tried to book an economy-ticket JFK-AMS-PRG-AMS-PRG with stop-over of more than 24 hours in AMS.

The ticket image shows (probably messed);

01 FLYERTALK/WEIGH ITINERARY REBOOKED
------------------------------------------------------------
AL FLGT BK T DATE TIME FARE BASIS NVB NVA BG

NYC
AMS KL 0642 B *B 01FEB 1825 BLXEPX 01AUG PC
PRG KL 1351 B *B 05FEB 0850 BLXEPX 01AUG PC
AMS KL 1352 B *B 20FEB 1110 BLWEPX 01AUG PC
NYC KL 0641 B *B 25FEB 1415 BLWEPX 05FEB01AUG PC USD 1353.00 01FEB05NYC KL AMS Q25.00KL PRG M589.00KL EUR 1013.00 AMS KL NYC Q25.00 M614.00 2S100.00NUC EUR 3.74YC 1353.00END ROE1.000000SOTO EUR 10.56US XT EUR 10.56US EUR 3.71XA EUR 5.24XY EUR EUR 89.25XT 1.87AY EUR 25.12RN EUR 4.00VV EUR 21.10CJ EUR 1116.55 EUR 15.40CZ EUR 2.25XF JFK3.00 RATE USED 1USD=0.74875EUR

**************************
At least it says PC on all 4 coupons.....

I dont know, but I would be VERY surprised if an check-in agent could deny you PC-based baggage when it is clearly written on the ticket....