Do you have the Doughboy Media Master 1900 filter? Strange, nowhere on their site or in the documentation to they say what the maximum pressure and flow rate are. But the flow rate won't be too different from other manufacturers.
After doing some quick research... A typical 20" diameter sand filter is rated to handle about 50 gallons per minute max. A 2-hp pump will be trying to push 80 to 100 gallons per minute (varying greatly depending on pump and plumbing). So, yes, without even seeing the exact specs for your equipment, one can deduce with near certainty that your pump is waaay too powerful for your filter.
Personally, with that size filter and that size pool, I'd think a 1-hp pump would be perfect. But I'm not an expert (yet!), so don't take my word on it. Hopefully a moderator will move this thread into the "Pumping Station" sub-forum, and you'll get some more educated responses.
Another thought... After backwashing, are you remembering to "Filter to Waste" (also known as "Rinse") for a few seconds before returning to regular filter mode? If you don't, that can send a little sand and debris into the pool. But this debris will be a one-shot deal, not a continuous accumulation in the pool.