Re-suggestion, thanks to Mindacos for pointing out the discrepancy!

Sale 1:

https://backpack.tf/profiles/76561198104098977#!/compare/1526947200/1528761600

https://backpack.tf/profiles/76561197998290686#!/compare/1528675200/1528761600

Sold for 20 keys + ~5 keys in sweets

Total is 25 keys.

Sale 2:

https://backpack.tf/profiles/76561198174748513#!/compare/1526083200/1526774400

Sold for 22 keys(?) Keys not showing up on Buyer side, but kinda undeniable.

Sale 3:

https://backpack.tf/profiles/76561198086793593#!/compare/1526688000/1526774400

https://backpack.tf/profiles/76561198093818959#!/compare/1526342400/1526774400

Sold for Duped Beams Handle

Handle Mini:

https://backpack.tf/profiles/76561198324455724#!/compare/1528070400/1528243200

https://backpack.tf/profiles/76561198094911935#!/compare/1527897600/1528243200

Sold for 29 keys

Only traceable duped sale I can find.

Sale 4:

https://backpack.tf/profiles/76561198093818959#!/compare/1528675200/1529712000

https://backpack.tf/profiles/76561198081780348#!/compare/1528761600/1529020800

Happened through Scrap bot, untraceable.

Total sales @:

22, 25, 29

Taking 25 - 29 keys, as 22 is closer to buyers(19.03)

https://backpack.tf/classifieds?item=Quack%20Canvassed%20|%20Sniper%20Rifle%20(Field-Tested)&quality=15&tradable=1&craftable=1&australium=-1&particle=701&killstreak_tier=0