Is it ok to submit a build to the app store for testing when a previous build is waiting for review?

I recently submitted an app for review, and it's currently in "Waiting for Review" status.

I'd like to submit a new build and enable it for testing in TestFlight. When I set enable testing on for the new build, the store shows the message:

"are you sure you want to start testing 1.xx.20?  Testing for all builds of 1.xx.19 will stop, and you will send an update to your existing testers"

I don't care about testing the previous version, but I don't want to disrupt the review process. Is it ok to go ahead and enable testing for the new build?