in cases when multiple releases would merge in single record, it will look like this:
4940261501860 (SLPS-02613), 4940261503710 (SLPS-03273)
it could be useful to know which release comes with which barcode - i do agree with that
but for Europe & USA serials would mostly be the same in those cases, so this won't work
for example:
Adidas Power Soccer
Original, Platinum
Air Combat
Original, Platinum

The different serials are missing from the examples posted here. It is very likely that these need checked for all PS1, this is not my area. A mod who is very familiar with PS1 and the serials should take a look at these things and everything else in the db and add/fix them.

Plextor PX-760A 1.07 (+30) : Plextor PX-716SA 1.11 (+30) : Plextor PX-W5224A 1.04 (+30) : Plextor PX-W4824 1.07 (+30) : Plextor PX-W4012TA 1.07 (+98) : Plextor PX-W1610TA (+99) : Plextor PX-W1210TA 1.10 (+99) : Lite-On LTR-48246S (+6) : Lite-On LTR-52246S (+6) : Lite-On LH-20A1H LL0DN (+6) : BenQ DW1655 BCIB (+618) : ASUS DRW-2014L1 1.02 (+6) : Yamaha CRW-F1 (+733) : Optiarc SA-7290H5 1H44 (+48) : ASUS BW-16D1HT 3.02 (+6)

I think both serials and barcodes are sorted alphabetically, you can't change the order.