There are a lot of options out there for a setup similar to what you're talking about. But honestly, there are big downsides to multi-optic weapons.
1st weight
2nd height above bore considerations
3rd Training required
The third point is really the big one. Under stress, (and I've seen this with the trijicon with red dot attached) people tend to go to the sight they use the most ie their main optic. Utilizing the top mounted red dot also means breaking your cheek weld, resulting in an unnatural, awkward position behind the weapon.
You're better off with either a) training, shooting, and training some more with the optic on your weapon to offset the disadvantages of using a magnified optic up close, or a red dot at long range. Or b) Look at a variable power optic, capable of dialing down to a true 1x (or close to it).
My $0.02. I am firmly in the variable optic camp.