This is typical view of ProE files saved in a folder. For a beginner this can be bit confusing and sometimes will lead to some problems.
What is it
Each time you save a ProE file, it creates an additional file (instead of overwriting it). file.prt, file.prt.1 etc. Next time you save and it will create another file with next higher serial number
When you open a ProE file through ProE, (File -> Open), it will only show one file for all such cases, in the normal mode. When you select a file, ProE will automatically open the latest one.
[Forget about the file type names that you see in windows explorer TYPE column. it doesn't matter]
How to open a previous version
But you can open the previous version, if you want to. In WF2, in the open dialog box, you will see an arrow at the top right corner. Click that and select all versions. (in WF4, i think its in the context menu). Then you can see all versions. Select the version that you want. and Open.
If your session is clean, you can also drag-and-drop the exact version that you need.
How to remove old versions (PURGE) of a file
If you are sure that you don't need previous versions of a file, then you can remove the backups. File -> Delete old versions.
How to remove all old versions (PURGE) from a folder
If you want to do that for all the files in a folder, then first set that folder as the working directory. Window -> Open System Folder. (dont know if I got the text correct). Then the dos prompt will come. type PURGE. close it.
Because of this, beginners may face some problems. Sometimes the problem happens when you copy some files manually using windows explorer. That's a dangerous thing to do and unless you know what you are doing. The problem happens if you copy a latest file into a folder which has the same file (older version with a higher serial no). Then ProE takes the higher serial number as the latest, which really is not!
If you want to save a file(s) to another folder, always do it through ProE. You can use File -> Backup. That's always safe.