The 2 important things are.
Don't bulb techs that have too little left or you will hit the cap (anything with 3 or less turns left should be avoided, if your blb is low comared to the tech cost however you're fine).
All your overflow accumulated go into a pool, so beware before bulbing more in that turn.
Your overflow gets zeroed on the next turn if you can dump it on a tech.
I am actually more interested in the mechanics of that separate pool for overflow. If you bulb multiple GSs in one turn you can get quite a lot of beakers in it.
Let's say for example at one point in game you can research 5 techs, 4 of them cost 400 beakers (A,B,C and D) and one costs 200 beakers (E). You are generating 100 beakers per turn and bulbing a scientist gives you 800 beakers. The numbers are unrealistic but that is not the point, just wanted to make calculations simpler.
The techs are queued in A->B->C->D->E order
At the beginning of the turn you will have 100 beakers in tech A. You bulb a scientist that will give you 800 beakers, + the original 100 that gives 900. 400 go to get tech A and you have a 500 overflow (you are safe since it does not go over the cap). From what I understand this goes into a separate pool and cannot (in any way) be used this turn. This is what generates the "maximum one tech per bulb" effect. So even though you have 500 science overflow and you have tech B queued up you will not get it from this bulb.
You pop another GS, you get B and now you will have 400 overflow. This will go in that pool to total at 900 beakers. You don't automatically get tech C for the same reasons you did not get B.
Fast forwarding you pop 2 more GSs (totaling 4 bulbs this turn) to get techs C and D. You are now left researching tech E, and with 1700 beakers in the separate overflow pool.
Now comes the interesting point, if you hit end turn. You will put in tech E: 100 beakers from BPT, and 1700 from your overflow pool. Since tech E costs 200, you are left with 1600 beakers overflow. Does this get capped at 500?
If not, then the overflow bug that let you exploit science was not fixed at all, and a player can still exploit this, but slightly harder: he needs to be careful not to overflow too much when bulbing, so basically he needs a situation with multiple techs that cost him no less than 3 turns and no more than 8 turns (in order optimum you need exactly 3 turns, the more you have the less overflow and at 8 turns there's little or no overflow), and also save a really cheap tech to queue first at the end of the turn.
I will assume that the overflow will get capped because if it doesn't, it is just ridiculous. I don't think the civ 5 developers came with such a lousy fix.
So, in my example you will research tech E and you will be left with 500 beakers, thus losing 1100 beakers (basically a scientist and 3 turns of research). In this situation the conclusion is that you CAN safely bulb multiple scientist in the same turn. You need to be careful not to have too much overflow in that separate pool, and at the end queue an expensive tech first. After each bulb you can check your overflow as Horseshoe_Hermi described in a previous post. You need to make some calculations in order to be sure you end the turn with a tech that costs you enough beakers so you don't overflow over the cap. You need to consider that your normal BPT will also be added next turn. So for example if you have 1700 in your overflow pool, and 100 BPT, you should queue a tech that costs at least 1300 beakers.
Is this right? I will try to test this tomorrow if I have the time.
