It's possible. You might want to try one stick at a time to see if any are faulty. Also, make sure you're using relaxed RAM timings (i.e. higher, like 3-4-4-8 for starters), in case the new stick can't handle the timings of the old one. They are both rated to run at whatever speed you've set them to right?
I’ve tested it and it’s not faulty. I’ve checked the timings and every thing but it still won’t boot up. My motherboard supports dual channel memory up to 4GB so maybe it has something to do with which slots I put the memory in. I’ll have to experiment.
If the modules aren't the same brand and model line, then it's most likely the two modules are conflicting with each other, and won't be usable together. But reset CMOS first and see if they work OK afterwards.