SQL weird relation

I have a DB with three tables where one act as an intermediate table implementing a many-to-many relation. What I don't understand is that there also exists one more normal one-to-many between the non-intermediate tables.

tbl1 (1 -> Many) tbl2 and
tbl1 (1 -> many) tblInterm (many -> 1) tbl2

Can someone explain why they have chosen this design?

Thanks!