Damaged 3 IP Cameras with replacement power supply
There are a few possibilities:


Are you sure the polarity of the output plug is the same?
Can you look at the output voltage ripple of both supplies on an oscilloscope?
It could be that there are load transients that the replacement supply doesn't deal with well causing overshoot.
Perhaps under load the replacement supply (even though it's rated at 2A) droops to the point where the input current rises enough to cause damage to something in the camera.


Most of those seem unlikely, and normally you would be fine making the substitution you did, but given that the damage did happen those are the possibilities that come to mind.