Menu has two drop down arrows

Hi, perhaps caused by a recent update but there are now two sets of down-arrows for my Menu, with a wanted sleek down arrow by the Main heading but underneath there is an additional line of space and down a deeper thicker arrow which when I inspect is fa fa-caret-down. I can't see how to remove this. I've looked on the forum but the only person who has mentioned this under menu dropodowns are glitching seemed to have resolved by updating. But everything is up to date. Only get this error on desktop, ok on mobile devices.
How do I remove this please? Thanks.