Yes, you probably would need to regulate the range of frequencies you see at a time unless you upgrade the brain to process the extra information, but it depends on how your vision is organised. Animals that see a wide spectrum tend to see in low resolution or with limited visual processing.
Rods and cones in the human eye are connected in groups to neurons called retinal ganglion cells (RGCs). The signals from each group are effectively combined into one pixel, with the number of cells per RGC varying across the retina.
Lower resolution per colour
If your larger eye has more rods and cones but the same number of RGCs, it will have the same resolution as a standard eye but better night vision and less "noise" in low light conditions. This will cause no problems for the brain but you might have some trouble adding extra colours.
You could keep the eye at the same resolution but replace some of the cones (or groups of cones) with cones that sense other frequencies. Then you'd have normal monochrome vision combined with poorer than usual colour resolution, leading to situations where you can read small letters in black on white but not in orange on yellow, for example.
The brain might need some modification to recognise the extra cone types, but there are already people with 2 or even 4 cone types instead of the usual 3, so it might be able to adapt as it develops.
An alternate solution would be to keep the standard 3 cone types but have each cone express two different pigments - the usual one plus one IR or UV band. Then use filtering spectacles or nictating membranes when you want to see only "normal" colours or only the extended palette.
If you add extra RGCs as well as more rods and cones, the eye will have more resolution and/or more colour depth. In this case you will need to upgrade the brain's visual processing system to cope.
The brain is already very good at filtering out irrelevant information, but it will need to do something to process the extra data before that filtering can take place. The visual cortex will have to increase in processing power (and physical volume) or simply work more slowly, unless some extra filter can be added to decrease its workload.
If your genetic engineers understand the brain well enough they might be able to add an extra filtering system that chooses only a few sets of cones at a time, effectively changing your colour palette depending on what you want to see, or compresses the whole palette into a colour space the rest of the brain can process quickly. But if they can do that, they can probably give the existing visual system more power to do its own filtering.