how do i delete duplicates if the only difference is date

Question

years ago i made a mistake of transfering my email from outlook to gmail, they were both set to forward to eachother so all emails bounced back and forth causing duplicates, i feel i have gotten rid of most but i have two folders left

name 1
name 2

it is possible that name 1 has all the original emails while name 2 only has duplicates, all emails in name 2 are incorrectly dated i want to remove name 2 but i need to make sure that name 2 only has duplicates

how do i only delete duplicates in name 2 comparing to folder name 1 and how do i do a mass duplicate search on my inbox, all duplicates have only one difference and thats the date they were copied.