Is it possible to use or race two RC at the same time?

Yes it is possible, in fact a lot of hobby enthusiasts race their RC Cars. This can be done if the two RC Vehicles use two different radio frequencies. Check your Vehicle, normally your cars frequency is written in the box.

You can change the frequency on some Ready To Run R/C cars, but not all. This is normally available on the bigger models like the 1:10 scale and on some 1:12 scale models.