Two main possibilities for upload to avoid duplicates

[emilyhopkins]

When user tries to upload, first encourage them to search the DB for that work.

If it's not there:

(1) User adds new work metadata and files at the same time

If it's there -- send them to the work record so they can:

(2) Add files to existing work in database -- work record includes "add files" option

Should help avoid duplicate records

[emilyhopkins]

"Add a Musical Work"

"Upload Files" for part, section, work as well.