Your MOSFETs should probably be thermally coupled in this instance. Any temperature difference can make a positive feedback loop, because the hottest FET tends to have the highest RDS(on). So put both MOSFETs close on the same heat sink.
That being said, you should also consider finding a high current gate driver for your MOSFETs, in order to minimize overall switching losses. Power MOSFETs have significant capacitance at the gate.
If you want to switch them fast enough through BJTs and resistors of your own design, you need to spend some time on designing and testing that. (The totem pole driver in Spehro Pefhany's answer would make a good starting point for that.)
An off-the-shelf driver is by far the easiest solution IMO, and quite possibly better than anything you can easily make from discrete components. For example, the TC4420 has 6A peak current, dual output channels (so one driver chip can drive both your gates independently), and can be bought for less than half a dollar. There are of course many others to choose from, so I suggest you find one that fulfills your particular needs.