This is just a preference buddy don't worry
singletapping requires less coordination and will usually grant faster returns. Alternating only really pays off for gaining ranks when you're REALLY good at it, and even then you'd probably be better off if you had spent all your time on getting better at singletaps. Unless you're one of the players who have a very hard time with it, some people are just really incompatible with the singletapping playstyle.
The only thing where alternating gives you an advantage, is maps that are too fast for singletaps. But of those, there are far and few in between, and they usually don't give much pp.
Honestly, if the only great thing about alternating is that it doesn't shred your tendons.
If you want to rank up and you have the potential? Singletaps are the name of the game. If you can singletap 260 comfortably, you're basically set for top1000, unless you're super sucky in all other aspects of the game.