Having the import of the same file twice, makes one of them useless. Leaving them in reduces the code's readability, since their presence can be confusing.

Noncompliant Code Example

@import 'a.css';
@import 'a.css'; // Noncompliant

@import url("a.css");
@import url("a.css"); // Noncompliant

Exceptions

This rule ignores @import in less files.