normally one would use say 2 regulators and 2 lipos for instance to power the receiver with one maybe 1600mah battery and then for ignition maybe 1800mah... how about just using one lipo with one regulator and splitting the supply to both the ignition and receiver... like have one 3000mah battery to supply both, can it be done? is there disadvantages? positives maybe? would like input from you guys... I will be using 9001MG PowerHD servos...

I would not do it, but there are many that like risk that disagree with me. Personally, I would not use a battery that required a regulator, but your location might prevent you from obtaining A-123 batteries.

I can get them... but Lipo lasts so long compared... in my DX7SE transmitter I use a Lipo and it lasts close to 2months before I need to charge... but I only fly weekends... the normal battery lasts only round 5hours maybe less so I replaced it... using Lipo is also lighter which is why I like to use them...

Most ignitions manufacturers advise against using a single battery for ignition AND receiver. They also advise against regulators.
Many ignitions will work well on one, or two LiPo cells, depending on ignition design.
In my tow plane I have:
3S LiPo for boxer ignition
5S2P Sanyo Eneloop on Emotec for receiver safety
5S Eneloop for on board tow line winch
1x Eneloop for Venom temp gauge

ek praat Afrikaans... dis baie naby aan jou taal... verstaan jy wat ek skryf? ek was laas jaar in Holland... Amsterdam meer spesifiek... ek kon heelwat verstaan wat die mense praat...

We have been flying with ONE A123 2300ma battery for two years now on at least
a dozen or more gas planes.. Ignition, receiver, smoke system and high torque servos on one battery... 50cc gas
After the first year with no problems we started installing a 1n 1001 diode before the ignition
just to play it safe...