My opinion - there has been a lot of bad advice stated hear.
Doubles are just a piece of equipment to use. Like singles, they provide air. They also can provide redundancy and better trim in some cases. They usually but not always provide more air than singles. They also have a few skills unique to that piece of equipment such as valve shutdowns as well but those skills need not be mastered to start using them. (lose the redundancy and add failure points yes, but for NDL diving, its the same bailout as a single tank)
To make a transition from single to doubles, it is very advantageous to have someone who dives doubles mentor you for a few dives. Lacking that, (or if you prefer), there are several pre-tec/entry tec classes that will help as well. GUE Fundementals, some Rec Deep diver courses* (IANTD is one), Naui intro to tec, Advanced Nitrox, Rec trimix are all good starting places. (*many rec agencies deep diver class do not include doubles or redundant equipement option. Padi for instance does not. Check before assuming for any agencies class)
Doubles are not "Just for Tec"
Doubles are not "Just for Cave"
Doubles do not equal "Deco"
Doubles are not dangerous to rec divers
Doubles, even without valve drills, still are OK for NDL rec divers.
More air doesn't mean problems for rec divers.
Bad air management is equally bad in big singles as doubles
Doubles are merely a tool divers can use at any level. If you plan to go farther into tec, start working with doubles and trim now. The last thing you want is to take an advanced (tec) class and spend half of it learning to use/struggling with your equipment. There are enough other things for you to struggle with.....