Mutiple svg background-images are not converted

[MrBemd]

If I want to use multiple svg background-images only the first svg is converted to valid output. The other stays untouched.

For example:

.background-with-overlay {
     background-image: svg("first-background"), svg("second-background");
}

results in:

.background-with-overlay {
     background-image: url("data:image/svg+xml, <valid converted svg>, svg("second-background"));
}

This is not perceived as a valid property in the browser, therefore the background image is not working.