You can only have a single one at any time is that correct? What I mean is that you cant have a couple of them to be able to be activated in que.

If you activate multiple of the 10% or 20% boots they will be queued to increase the total active time.  I believe this cannot be done with the 50% boosts, as the system will usually only let you buy one of them at a time and won't give you another one until you use the first one.  

That's what I thought, woe to the person who bought the Black Friday packages thinking they were getting 3 of them. 

Another Payrium scam.