That explains why Pokémon Diamond and Pearl were not working on the Yoshi Island DS driver then.
When the YS one came along they suddenly worked.
It also explains why Diddy Kong Racing DS works on the first playthrough and then when it loops, instruments on some songs drop. The drivers are slightly different as they go on.
I assume that this is a completely different driver altogether? (Seeing as they are contained inside another file and not just in the SDAT.