I hope this has not been asked but when i duplicate objects blender makes the original and the duplicated as one object. For instance, i am not able to add two different materials/textures to the original and duplicate
after you duplicate, in the Material panel, next to the name, you will see a 2. that means that 2 objects are sharing that Material. Click it to make a single user copy for that one object. now your changes are independent.
It is confusing since your two posts both say different things:
The first one could mean that you used Alt+D, which makes instances of the same Mesh, which means that they share materials and objectdata as long as us make them Single Users (by pressing u in Object Mode).
The second one could mean, that you duplicated in Edit mode and that the “object” are not really two objects but actually the same mesh. Therefore you can’t have two different materials on them (well, you can by using mutiple Materials on a mesh but that’s not the point here).