By "different voltage" do you mean slight offsets? Or do you mean design for 12V vs. 48V? Also: What kind of turbines are these?
Alternator-rectifier-no-regulator wind turbines are voltage regulated by the battery load. If they're appropriately sized for the battry voltage you can just hook 'em up - the rectifiers also serve as the blocking diodes. (Wind turbines with an internal voltage regulator, and generator-types, may have some issues. They'll also have issues with an external blocking diode, because the diode voltage drop will confuse the regulator about the battery state of charge. You'll have to look into each one to see if such a connection is suitable.)
Solar panels are also happy to be parallel-tied to the batteries through individual blocking diodes (which may already be part of the panel - check yours). They're inherently current-limited devices, so if you hook a 48V nominal panel to a 12V battery it will work fine (though you'll waste 3/4 of your panel's potential output.)
Just be sure you have a dump load adequate to handle all this generation, so you don't overcharge the battery.