Stacking cashback sites (TopCashBack, Rakuten, Swagbucks) possible...?

I'd think it's a no but I'm not sure how they'd be able to tell?

I have a specific web browser I make purchases with that has all the cashback sites' extensions. When you visit and eligible site, you get a popup like this.

I've never tried stacking them before, I just go with whichever has the highest cashback %. But I'm wondering, would it work? Has anyone tried it?