Prevent Submissions of Duplicate Runs

[albinohat]

I caused an issue on an account when testing a script to "copy" the runs of one account to another account. I ran the script a few times and as a result, multiple copies of the same run exist in the new account.

Possible solution: Add an "id" field to the payload of a submitrun-type JSON payload. If the id is already in-use, the run cannot will not be submitted.