Can i dye my hair twice after 6 weeks?? Please read info..?

Ive dyed my hair 5 times in total over about 3-4 months..the most recent one had no ammonia in and only lasted about 3 weeks (it was only a tint colour) so its pretty much faded back to the full brown...but ive still left it for about 6-7weeks just to be safe and to build up more strength/repair a bit so would i be able to dye it now without any hair falling out??? Thats the only thing im worried about, i dont want it to start falling out..lol! (my hair is in healthy condition, never had problems with the other times i dyed it and i use shampoo & conditioner). Also i would have to dye it the same dark brown i already have on before dying it the actual colour i want it (deep red/mahogany colour). only dying it brown again first because my roots would be a different colour if i did it red straight away :)