Code completion items appear twice when pressing ctrl+space

Describe the bug
Code completion items appear twice when pressing ctrl+space

To Reproduce

1. Write a table with some functions / fields.
2. Access the code completion for the members of the table by typing the table name and a dot.
   
3. Press escape or click at another position with the mouse so that the code completion window disappears.
4. Go back to the position after the dot and press ctrl+space. In the code completion window, all items appear twice. By typing a key, the duplicated items disappear.
   

Expected behavior
All code completion items are only shown once.

Environment:

• OS: Windows 10
• Client: VSCode 1.61.2 with Lua extension 2.4.7