UPDATE - I made some inquiries as to what exactly Pre-Algebra is in my area and it seems Common Core has left a bit of confusion.

According to the state pre-algebra is certain strands of 7th and 8th grade math.

According to the district it's certain strands of 6th, 7th, & 8th grade math.

According to our school, pre-algebra is 8th grade math.

My DS took 6th grade math last year with a GT teacher and he's taking 7th & 8th grade math this year with a regular education teacher. So..... no matter whose definition you use, taking pre-algebra next year would be repeating skills.