You don't need two enlargers to do b&W and colour, you only need one enlarger.
In fact, in theory you can do colour negatives on a b&W enlarger but it's a hassle. Perfect colour negatives don't need any adjustment, you can just shine perfectly white light through them and print. But in reality, It's pretty damned rare that you are getting absolutely perfect negatives.
So to use a black and white enlarger to print in colour, you have to get a multitude of little pieces of plastic colour filter material and mix and match them in the filter drawer of your enlarger while simultaneously keeping them free of dust and scratches.....
OR....just buy a colour enlarger and use the dials.:mrgreen:
A colour head just has the ability to mix a colour with the light coming out of the bulb to change the overall colour cast of the final colour print. To print black and white you just set them to zero.(usually, but I won't get into the variable contrast paper thing right now)
If you are just starting out, get a enlarger with colour head. I'd also recommend getting an enlarger that does medium format negatives, so you can buy a cheap medium format like a seagull, and make large prints that will make your digital friends less snotty and more envious.
I'm not just giving this advice, I'm also taking it.
I've got two enlargers, a beseler printmaker (small 35mm enlarger) and a Beseler 45mxt (a very large motorized enlarger that takes 4x5 inch sheet film negatives as well as 120 and 35mm). At the time, I was obsessed with black and white so I "saved" a little money and didn't bother getting one with a colour head.
I'm now in the market for a colour enlarger, probably 120 film format, to make colour prints, because my GF isn't so hot on everything being in black and white, and I'd also like take a few pics of sunsets.
I also realise now that colour printing isn't as hard as some people make it out to be, and my fears were probably unjustified.