PageId conflict when merge 2 Confluence Server

[Eddie Chang]

We plan to move from Confluence Cloud and merge into another Confluence server. The plan is to restore full Confluence cloud backup onto temp server then select Spaces to migrate to target server.

There might be some conflict pageId. If that's the case, what's going to happen? 

Will there be a pre-check tool for conflict before server-to-server migration?

What's the best practice for resolve the conflict pageid? 

Thanks