Thank you for your post.
I am unable to replicate the issue. With a file being hosted by FileMaker Pro 13.0v3 under Windows 7, I accessed the file using FileMaker Go 13.0v4. I then started to edit a record in FileMaker Go. I then went to the Windows 7 machine and tried to edit the same record, but I get the message that the file was currently in use.
Is it possible the connection was lost? This would account for the PC to edit the same record as FileMaker Go, but you would also see that any changes made by FileMaker Go would not be updated to the PC because the connection was lost.
Any other information you can provide may be helpful.