yes different colors of ink are removed by different colored lasers..i believe only 2 colors of lasers are used. after time the area can be tattooed over. i would not recommend any other type of removal as they can't get deep enough without causing pretty bad trama. the more trama, the harder it will be to tattoo over again, if that's your goal.
most tattooes can be covered alot better than people realize. take the time to find someone that is highly experienced in cover-ups to consider if that's an option. if you have any other questions about tattooing ask here or pm me.