NOTE: I've posted this on StackOverflow but it got deleted so I'll post it here. This worked for me so it might work for you.
If you open up a VS Database Project and get a weird error like "SQL71566: Microsoft.Data.Tools.Schema.Sql.SchemaModel.SqlFilegroup cannot not be set on both the Microsoft.Data.Tools.Schema.Sql.SchemaModel.SqlTable and the clustered Microsoft.Data.Tools.Schema.Sql.SchemaModel.SqlPrimaryKeyConstraint" on one machine but it works fine on another, then read on. Some may find the solution being to upgrade to the latest SSDT but there are some who (for legacy apps) can't upgrade the project.
Be aware that SQL Server Data Tools installs the SQL Server Data-Tier Application Framework. If you uninstall SSDT, you'll have to manually uninstall SSDAF. You should then only have to install SSDT but you'll have to look at your Control Panel to see the versions of each. If your versions are the same as your coworkers then you should be good. Otherwise you'll have to install each separately (not fun).