problems of power combining in PA

when i use two power transistors for power coupling ,connect the two gates and drains together and use one gate bias and drain bias circuit,Is it possible in practice? are there any hidden troubles?
during simulation,i found there is a peak in gain curve at a freq point,At first,i thought it was resulted by the bias circuits,but even biasing the two transistors respectively,it's the same case.what's the possible reason of the peak?
many thanks!

Paralleling two or more transistors does not mean "power combining".
Power combining consists of "combined powers" that can be delivered from each transistor independently.So, each transistor should have own RF circuitry( they may share biasing circuit with paying attention) and output power must be combined by aid of passive ( or active) combiner circuits.

The peak which you saw may have a bad news for you like "unstability" at certain frequency.So , you have to pay more attention to implement such circuit.

A classical problem in paralleling devices goes back to the days of valves/tubes. This is a push-pull mode of oscillating.

Another problem is that the load and source impedances are halved which makes for narrow bandwidth networks and higher losses.

I would recommend that you design two identical amplifiers one transistor each and then use quadrature hybrids to combine them.

you said it ,it get more difficult for broadband matching.Before this,i used Lange Coupler to implement the balance amplifier.because of the precision of PCB,Lange's parameters didn't accord with the expected ones.hence,the balance amplifier failed.The most serious problem of all is that it is very difficult to debug the circuit since it has two RF circuitry.
so i use two parallel transistors as one,which structured only one circuitry.i thought it may be much more convinent during debugging.Is it?

When doing development, test the smallest increments of the circuit at a time instead of the whole works. Try out just one amplifier by itself first.