"Onion" and "salsa" possess a similar structure:
both words consist of two identical
2-letter syllables and a distinct letter between them.
Apparently, there are more English words of similar form (12312).
Find as many as you can.
(In reply to Solution
by Dej Mar)
Kudos to your comprehensive and educating research.
It will be my pleasure to post it as an official solution,
naming the contributor, of course
I am sure that anyone reading your post enriched his/her vocabulary.