Upvote:2
Yes you can, a friend of mine applied for F1 while holding a valid B1/B2 visa. His F1 was approved but they cancelled his B1/B2 visa.
Regarding not travelling to the US using the visa you issued, there is nothing official regarding this, it will be at the discretion of the interviewer.
Note: I hold two different types of visas now, B1/B2 and D, both are valid and I am using both.