Are either of the brooders of a size that they can be easily divided and leave enough room for each group? When you are ready to integrate (timing will depend on whether you plan to do a proper quarantine or not), the easiest thing to do is to house them so they can see each other but not have physical contact. A wire barrier works wonderfully - as does a cage of sorts set inside a larger area. Let them get used to seeing each other over a period of days and then remove the barrier and allow them to mingle. Monitor for signs of trouble, but remember there will be squabbles - intervention should only take place if serious physical injury is occurring.
The good news is that 2 weeks age difference is not significant enough to cause concern about size difference, etc and both groups are of an age where there are not huge gaps between their environmental needs.