Keystroke duplicating in data grid
Please try the following possible solution:
1. Go to the following directory in c:\ drive:  

C:\Users\&lt;your_user_id&gt;\AppData\Roaming\



There you will find folder(s) named SQL Developerandsqldeveloper
Rename those folders (whose name is like SQL developer and sqldeveloper) to something like SQL Developer1 and sqldeveloper1 respectively or as you like.
Restart SQL Developer application.  


Note: After performing the above operations  all your Connections data will get erased. So, you might need to first export all your connections into an .xml file.  

Hope this solves your problem !!