This method works better the more money you spend.
A new tab will open with your ad and a link that looks something like this.
"facebook.com/10000000000010…"
Copy and paste the second long number at the end of the URL.
You are using one ad in all of your ad sets, instead of the same ad with different post ids.
The more you spend the faster it will accumulate social proof!
Typically, I will have anywhere from 4-8 existing ads under one ad set depending on the type of spend the account is doing.
Social proof is a must have, especially for ecommerce stores!