Enabling externalQuery results in "Duplicate keys" errors occur in 2.21.6

[dorabt]

Issue Type (delete the irrelevant ones)

• Bug

Specs

What version are you using?
2.21.6

What browser?
Chrome and Firefox

Expected Behavior

What did you expect to happen?
I expected the table would simply be displayed without error.
My app worked fine on 2.21.5.

Actual Behavior

What actually happened?
Duplicate items were displayed in the table and I got multiple "Duplicate keys" errors in the console.

Steps to Reproduce the Problem

I made a simple sandbox. (sorry. I'm not very familiar with jsfiddle.)
https://codesandbox.io/s/vue-good-table-2216-04us4

This problem seems to occur when I put ”externalQuery" in search-options. It was the same when I put the "trigger".
This sandbox works fine when I downgrade 2.21.5.

Thank you for your great work.