It is not about displaying but setting the hud message.
Code:
set_hudmessage( red=200, green=100, blue=0, Float:x=-1.0, Float:y=0.35, effects=0, Float:fxtime=6.0, Float:holdtime=12.0, Float:fadeintime=0.1, Float:fadeouttime=0.2, channel=4 );
The channel ( the last parameter ) should not be the same in the messages you want to show at the same time. Set the messages separately and set the both channels to -1.