I'd warrant nearly all of them, though it may take a while.
If you have ever submitted or worked with a bug bounty program you will run into dozens of duplicates.
I've personally performed and overseen assessments in which the company had already done a complete blackbox pentest and wanted a second whitebox review to make sure the first company knew their stuff and validate they found the same bugs. Also did a few of the honeypot assessments in which companies put purposely vulnerable code in to make sure 'we are doing our job', I hate those most.
Depending on the testers speciality of course, the reports often found the same or similar issues.
Source: 15 years as a pentester, offensive security engineer, and now security architect.
Why guess when the other commenter has the actual data...?
His eventual response was 0, by the way.