LR classic imports doubles of all of my photos

I just imported a folder of 77 photos from a different (old) computer.  But, when I look in the Previous Import folder on the new computer, there are 152 photos.  I can understand that some may be virtual copies.  However, they are all doubles, with the exact same time stamp on them - they are duplicates.  Please help. How do I avoid importing duplicates of all my photos - this has been happening the last few days.  I always check "do not import suspected duplicates", but it doesn't make a difference.  I can easily delete the extra 77 photos by hand, but what about my folders that have 100's of photos?  Any suggestions in easy-to-understand terms would be greatly appreciated.  

Moved from Using the Community (which is about the forums) to the correct forum... Mod
To find a forum for your program please start at https://community.adobe.com/