My Dreads are growing together at the roots! - Dreadlocks FAQ's
Dreadlocks will always want to grow together and combine at the roots. New dreadlocks are notorious for "hooking up". As they mature it will occur a little less, but any time that hair from one dread ends up locked in another, you're going to see some serious dreadlock PDA.
There are two main things you can do to prevent these dread relations. First, while they are new, having a rubberband at the roots of each dread will help keep them apart. There are other advantages too, check out the maintenance section for a page on using rubberbands. The second thing you can do is pull loose hair at the roots into your dreads as you discover it. A Loose Hair Tool is the easiest way to do this. Hair that's pulled in to the right dread can't attach to the sexy dread next door. The more loose hair you have the more promiscuous your dreads will be.
Sometimes two dreads are so attracted to each other they find a way to combine when you're not looking. If this happens -and you don't approve of their union, the best thing to do is rip them apart. Grab one in each hand and pull in opposite directions. R-I-I-I-P. You get used to it, I promise - but others don't - so it will probably freak them out. Good times. =]
Rip them apart without using scissors. You'll do less damage to the hair this way. You'll create some loose hair when you pull them apart. Pull it into the correct dreads with a Loose Hair Tool and you should be good to go! If you don't pull it in the dreads will likely attach to each other again using the same hair.