Take a chance. Try it and let us know how it works out. 

Myself, I have cast bullets with two molds many times with no problems. Have heard that some casters prefer to use two molds. Sometimes a mold will get to hot, casting with a second mold will keep the problem mold from overheating.

I cast with two molds 90% of the time.i find it works out well.Sometimes I'll let one mold "rest"  if its overheating and cycle the other two or three times.it just depends on the molds material and "temperment"
Pot temp all the way up and cast fast

I regularly cast with two sometimes three molds,and when they're up to temperature I just set them down on the pad where I catch the bullets. Works great for me. 
Lee Gibbs Pres.ASSRA

I’m thinking that your overall productivity would go up without a decrease in quality. For me when casting heavy bullets 535 gn + I wait about 13 to 15 seconds after frosting appears to dump the bullet, at that timing no pits in the sprue cut and the bullet has shrunk enough that it falls easily, but I cast at 815. In that 13 to 15 second wait I could charge another mold. That’s where the time would be found I believe.
Richard

It only takes me about 50 minutes to cast a 120 match grade bullets using but one mould. As soon as the sprue freezes it is cut off and the bullet dropped and I very quickly re-fill the mould again. I keep up this same cadence going all the way to the end of a 120 bullet batch. Bullets come out weighing within 4 tenths and then are visually inspected for any noticable flaws. That is what the extra 20 are for and I usually end up with about 10 give or take in a 100 bullet batch and if not used they go back into the pot. I also cast at 800+ degrees and I do Ladle pour and I also shoot them in the order as cast. But I also only shoot competitively and if I did not it probably wouldn't matter all that much just how I actually went about it. I also use an Ove Glove and cut the sprues by hand. If required a small tap with a plastic mallet is also used to get a bullet to drop out. Pot is also a Lyman Mag 25 Digital Melting Furnace and alloy of choice has typically been 1-16. So far the Lyman Digital pot has been holding a constant temperature quite well and nothing goes back into the pot until the entire casting session has been done. Not sure if this is of any help and just wanted to share abit more on how I go about it for my own personal usage.

JohnL
Thanks for posting your concise bullet casting tutorial. As you know a thing or two about accurate BR shooting with cast bullets, your techniques are well worth knowing. In the contacts you and I have had, I've picked up valuable tips on improving the quality of my cast bullets.
Keep up the good work.

Thanks to all who responded.  I have a digital RCBS pot and am ladle pouring.  I set the temperature to 800 degrees for today's run using 40:1 foundry alloy.  I preheated an aluminum 50 caliber 515 grain mould and a 40 caliber 400 grain brass mould on my hotplate.  I cast 10 sacrificial bullets from each mould than cast for keeps by running moulds alternatively and then setting the mould waiting to be emptied onto the hotplate set just below medium.  I cast 60 of each and decided that the pot was getting low enough to end the session and see what my results were.  To begin with, whether it was the increase in casting temperature or letting the mould cool longer is hard to say as I had two variables at play, the bullets tended to drop out of both mould pretty good with a marked improvement in the 50 caliber aluminum one.  Second, the aluminum mould was ready to cast good bullets sooner than the brass 40 caliber mould.  I had only  three fifty caliber bullets that failed my weight criteria of plus or minus 1 grain for a 515 grain bullet.  The brass mould had seven rejects.  After the rejects were culled, both moulds produced a bell shaped weight curve.  All in all, a very rewarding experience.  My next session I will try just a single brass mould, a 40 caliber 350 grain gas check bullet, with the 40:1 at 800 degrees and see what happens by cast about 150 bullets an hour or so.  So far my experiment of using 40:1 alloy in my 40-70SS at 1600 fps has been successful with good accuracy and no leading.  The 50-70 is about 1300 fps I guess and again very accurate and no leading.  I have pulled the scopes off of my 50-70 Roller and 40-70 SS Sharps and it is time to get my hunting loads fine tuned.  I think I might stick with black in my 40-70 Hepburn just because I need one hunting rifle dedicated to the way it was done in 1880.  Tom