Autodesk Navisworks is a collaborative solution, and although users may be reviewing the model in different ways, their resultant files can be merged into a single Autodesk Navisworks file, with any duplicate geometry and markup automatically removed.
When merging multiple NWF files that each comprise the same referenced files, Autodesk Navisworks only loads a single set of the combined models, along with all review markup (such as tags, viewpoints or comments) from each NWF file. Any duplicate geometry or markup is removed when merged.
For multi-sheet files, it is the currently open sheet/model, which is the recipient of the merge command. If you are merging two multi-sheet files together, once the default sheet/model is merged with the current scene, you have an option of adding the rest of the sheets/models to your file. You can customize this behavior in the Options Editor (Interface 
Appending and Merging). You can also perform geometry and data merge from within your file, that is merge 2D sheets or 3D models listed in the Project Browser with the currently open sheet or model. See Add Geometry and Metadata to the Current Sheet/Model.
Merging TimeLiner Data
For files that contain TimeLiner data, merging is done as follows:
- if two TimeLiner data sets are identical, all duplicate data is removed.
- if two TimeLiner data sets contain the same Primary link, then the data set with the most recent link (that is, the newest file date) is chosen over the other. If the Primary links are different, then the data set with the highest number of tasks will be used, and links are re-attached wherever possible.
- if two TimeLiner data sets are completely unrelated, no data merging is performed.