A nice approach on the matter about there being previous tracks or not would be contacting mtumesalaam, who added the two cds on the Discogs' database and sold them to Almamu. Maybe the person can give us more context about the tracks or where he got these and if there are more to find or if Mike/Joe were really featured before.
This person deserve some of the credit too you know, I mean if it wasn't for him/her maybe neither Derek nor Almamu would get a hand on these tracks. Just imagine if one of those collectors that "doesn't share anything and fuck the world" bought these instead haha