After getting advises from the pro users here I decided to buy IO and IShine for me to use at classes. I have one question. is it okay if i buy the 2x strength version?
I would say so - neither of these contain none, so you have nothing like the same OD problems. Most of us pull fairly high doses of these at times, so the 2x is a good economy measure. 
Well the 2x strength version would not be ideal for sweet spot testing, but like mobo said, those pheromones are highly social in nature so you should not fear an OD. Unless of course, you’re one of those people that may feel beta from too much socials.
thanks for the advices 
ordered one from each 2x strength
Really you only need to concern yourself with the None and Rone based products when considering 2X. It’s easier to overdue it with them. With socials you should be A-OK