Verification means getting the certified true copy yourself, reading every annotation, matching the technical description to the ground, and checking taxes, occupants and the seller’s authority. The copy the seller shows you proves nothing on its own.
Sometimes – and never against registered land. Whether decades of occupation turn into ownership depends on whether the land is titled, privately owned but untitled, or public land, and on the character of the possession itself.
A certificate of title proves ownership of registered land. A tax declaration does not – it is a tax assessment record that at most proves possession. Here is what each document does, what to do if you only hold a tax declaration, and how to get untitled land titled.