2 PRs with the same id in the same repo

I migrated 90 repos from an instance of github enterprise to another instance, using the methods described here : Migrating data to and from your enterprise - GitHub Docs

It migrated everything, even the PRs. However when I tried to create new PR, instead of incrementing the latest PR number, it started at #1. Which causes to have 2 PRs with the same id #1…And when I click on the new PR that I created, it redirects me to the old one.

Can anyone points me where I should start looking to fix this issue?

Thanks