Closed alpha testing tracks how to differentiate between two test tracks?

We are using Google Play Alpah testing tracks which can be tested by different testing teams for their respective modules.

But the links generated by these tracks are same how to get an application for a member which may be added to multiple closed alpha testing tracks.

e.g. We have two tracks Alpha Track 1 and Alpha Track 2, we have few common tester emails in these two but most of them get the apk from Alpha Track 1 which is the first created track. How can they install apk from Alpha Track 2 from their testing email accounts? Or do they need to have totally different email id for each track?

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