Starting kegging, regualtor question

I hope this is an easy one:

If I buy a dual gauge regulator and later decide I want a double regulator, can I just take off the high pressure gage and attach another regulator?

In most cases, yes. The thing you have to be careful about is the threading on the low pressure guage. For example, the low pressure Perlicks that were sold by American Science center were LHT, even though they had a TapRite body. My TapRite regulator and body had RHT.

So I had to find the rare LHT to RHT threaded nipple.

In the end, if you have to, you can thread on some barbed fittings and tubing to make ends meet.