Yes those photos had their correct dates in iPhoto. I carried on on with exporting and found other photos lost different metadata too - location, lens information, keyword, etc. a few photos appeared earlier in the day on Photos than they do on iPhoto even though the time stamp is correct. I deleted and tried again and they’d imported with the metadata or lose different metadata. The majority of photos were fine. I don’t know if I’m going something wrong or what but I’m going to try a different method . I’ll upgrade to larger iCloud storage later today, each library the system default one by one, and return to my main photos and let it download the new photos in iCloud.