https://backpack.tf/item/3147976579

I agree, dupe sales are finnicky.

Typically, you can just look at the id and see when it increases and between who it increases from.

Sale 1 - Rubi >> Crummy

https://backpack.tf/profiles/76561198002757046#!/compare/1616803200/1616889600

https://backpack.tf/profiles/76561198053720151#!/compare/1616457600/1616889600

36 keys match

https://gladiator.tf/listings/605ff5e35a25179a39c7542e - buyout 50, could add Crummy to confirm

Sale 2 - Crummy >> Ender

https://backpack.tf/profiles/76561198053720151#!/compare/1616976000/1617148800

https://backpack.tf/profiles/76561198177872379#!/compare/1616976000/1617062400

13 keys match

Sale 3 - Ender >> Mini

https://backpack.tf/profiles/76561198177872379#!/compare/1620000000/1620086400

https://backpack.tf/profiles/76561198116948434#!/compare/1620086400/1620172800

65 pure sale you already have

Sale 4 - Funny engi >> returning june 22nd (f)

https://backpack.tf/profiles/76561198323505653#!/compare/1618531200/1618963200

https://backpack.tf/profiles/76561198355068405#!/compare/1618790400/1618963200

Sold for:

Strange Specialized Killstreak Original - https://gladiator.tf/listings/607f7599dbd0d2e5a7bf552f - 50 keys at the time

Taking sale as 50 keys

Sale 5 - returning june 22nd >> Flarez

https://backpack.tf/profiles/76561198355068405#!/compare/1619568000/1619740800

https://backpack.tf/profiles/76561198099141522#!/compare/1619481600/1619740800

It would appear to have sold for:

Hot Sweet Toothed War Paint (Minimal Wear) - no mini as far as I could see, it's 25 keys at a minimum and there's a 1 month unsold at 40 keys

15 keys

~3 keys in adds

https://gladiator.tf/listings/608ad67bdf7f0c12bf09d946 - buyout 63 keys

Hmm 50 - 65?