Yes, filling out the form for collector status will allow you to buy more than one handgun per month. Basically, if you are qualified to legally buy a gun you will get the approval. In addition to getting the form from the state police, many gunshops will have them if you ask.
Incidentally, you can already buy more than one a month. MD's one handgun a month law has a couple "loopholes". You can buy two at a time so long as you buy them in the same transaction. Then, you have to wait two months instead of one month before you can buy again. Also, anything that qualifies as antique under federal law is not considered a firearm in MD for purchase (for purchase only, do not try to buy a blackpowder gun and carry it- once you own it the gun is now a gun and falls under MD's restrictive carry and transport laws). So, that means if you are into blackpowder or cartridge firearms made prior to 1896 (or is it 1898) you can buy as many as you want as often as you wish.
Personally, I refuse to get the collector status. It has helped keep me from spending much more on guns than I probably could have afforded comfortably (a few years ago I was adding guns pretty fast).