Auto completion not work properly when complete is.* and as.*

[Purkinje-cell]

I'm writing R markdown in VS Code when I find a weird error When I type is.data.frame or is.na in an .Rmd file, it will have auto completion options like this:

then if I click Tab, it will give an redundant is like:

but when I write my code in normal .R file, this problem does not exist.

I wonder what caused the problem and how to fix it

[eitsupi]

duplicate of REditorSupport/vscode-R#821