If you import two versions of your block file, you must choose which one you want to use. For example:
Libero recognizes a duplicate definition of <block1>. One from the HDL and another in the imported block file. The Design Hierarchy tab shows a <block1>.cxf and <block1>.v file under Duplicate Modules. Libero uses the HDL <block1> by default.
To overwrite the default behavior and select the Block definition, right-click the <block1>.cxf file and choose Use This File. When you update, the Block icon appears in the Design Hierarchy.