some ps2 backups in bl/w

[bad_juju]

a few days ago i modified my PS2 with the MESSIAH-modchip.
all original PAL games playback fine.
all PSX PAL/NTSC(j) backup's/originals playback fine too.
i d/l'd some PS2 backup's and some ONLY playback in BL/W!!
i'm not sure wich are ntsc or pal.
can it be those iso's are patched? or do i need to patch them to play on a PAL machine with the messiah chip?
does any1 have a similar prob? does any1 have a solution for this?
i have a V5 PAL PS2.