This is hardly new. I personally was aware of 3 different ways to get items for a lesser amount, and at least one way to get items for free. I hadn't heard or known of being able to get items for the cost of the least expensive of multiple item purchase, or shop free after having paid.
Two of the ways to get items for less are via use of Firefox browser extensions readily available, the third is doing the same thing the 'old fashioned' way. (all 3 are basically the same thing)
I was not aware of hacking other sites/services in a similar way.
The other way I was aware of was manipulation of browers and/or browser windows during checkout. There has been tutorials for all these methods published on video and websites for at least 3-4 years now.
Sadly, it appears that paypal will be 'fixing' the problem by freezing, seizing, delaying and holding funds from buyers rather than correct it's already hacked, cracked and zombied site. Hilarious!
I'm not sure where this thread has devolved into, this snippet from the original post says it all:
[...] After 24 hours I called PayPal and after pushing them, they completed their review and released the payment to sellers. If I hadn't called, they said it might have taken "another day or so" to review. The reason for the problem: I paid two sellers -- and I paid the cheaper one first. [...]