Many single-hopper machines have a little flap, drawer or similar opening where you can add ground coffee for one serving.
If you add one type of beans in the machine’s hopper you can use the second slot for the other.
The fact that the second one takes ground coffee doesn’t mean that half of your coffee drinkers have to use pre-ground, a good grinder should cost way less than a second machine or a dual hopper one. Just decide which group gets to use which setup. While we instinctively might say that the group that drinks more gets the simplest “just push a button” solution, maybe one fraction actually likes the “ritual” of the separate grinder.
As per request, I checked for examples.
This is the machine at my office: A BOSCH VeroCafe, you can see the opened chute.
The JURA machines I checked (randomly on the website) all feature “powder recognition for additional ground coffee variety”.
For SAECO I checked the (comparatively cheap) Incanto model and yes, this also has the “powder option” feature.