Many thanks to a very smart member who has hopefully identified the source of the double-login prompts some people experience when logging into the site. It looks like it is to do with the fact that the site handles requests to both restrainedelegance.com and www.restrainedelegance.com. It definitely looks like this can cause the issue, and it may be that changes rolled out to browsers might have made them more strict about whether the login cookie was for one or the other of these. I’ve asked tech support to check through and implement redirects which should hopefully fix the issue.
Sorry it has taken so long to figure it out – there wasn’t a lot I could do given that I couldn’t reproduce the error myself. And many thanks to the clever member for tracking it down! Hopefully that’s all it was, because if so the fix should be pretty simple to implement.