We have a play that is multiclassed level 3 arcane trickster and level 3 artificer.

However, they have two second level spell slots, which shouldn't happen for artificer until level 5.

I made a duplicate character and found the same thing.

What's going on? Thanks!

Multiclass spell slots are based on your total levels, so you don't fall too far behind single-class casters. 

The arcane trickster counts as one level, and the artificer counts as two (half your artificer levels, rounded up, from the class description), so you count as third level on the spell slot table.

Thanks that makes sense!