Is it possible to have 2 Adrev accounts?

Basically my old electronic music project that I release songs with occasionally has has songs uploaded to youtube loads of times on different channels (some reaching nearly 1 million views)

Is it best to make a separate AdRev account or can I just upload my songs to the same account?

Just use the account you already have. You enter artist information on a track-by-track basis. And do it quickly since you seem to be missing out on thousands of dollars.