Hello, Howard.
Duplicate folders appearing suddenly is usually caused by a Sync Loop. You can get a Sync Loop if you have (a) Synkmark on more than one Mac or (b) are still using Xmarks in addition to Synkmark. While it is possible to have both (a) and (b) and
not have a Sync Loop, one must be very careful. Such a configuration is not recommended because there is not too much to gain but a lot of pain possible if you ever switch on a checkbox by mistake and create a Sync Loop. Here is
more information on Sync Loops. To avoid Sync Loops, we recommend (a) use Synkmark on only one Mac and (b) don't use Xmarks – I see they are shutting down at the end of this month anyhow.
If you don't have a Sync Loop, well it is possible that Chrome's
Sign In, or
Firefox Sync, or
Opera Sync or
iCloud:Safari had a bad day and created duplicates. This can happen because there is always the possiblity of ambiguous data in syncing, and these services reasonably err on the side of creating duplicates rather than losing bookmarks. But, I don't know –
iCloud:Safari is the only one I've ever witnessed making duplicates all by itself, and the last time was several years ago. I think Apple has it working much better nowadays. Anyhow, if you think that any of these services was involved in a Sync Loop, you should remove all items from them and export from Synkmark onto this clean slate. Here is the
procedure for iCloud-Safari – the others are similar.
I don't know of any way for Synkmark to create duplicates. Of course, if one of the synced browsers gets a bunch of duplicates somehow, Synkmark will copy the duplicates to your other browsers, which is why we have Synkmark's
Safe Sync Limit preference set to 25 by default.
Synkmark and Xmarks are the only two services I know of that can automatically sync bookmarks between Firefox and Chrome. So the fact that you got these duplicates in
both Chrome and Firefox means that either you still have Xmarks running somewhere, Synkmark's Safe Sync Limit is set to more than the number of duplicate items. (Safe Sync Limit counts each child or descendant separately. For example, a new folder containing 10 new, moved, or newly-duplicated items counts as 11.)
Regarding Opera, starting with Opera 48, they made it impractical for other apps like Synkmark to use the equivalent of our
quick direct sync method so, yes Opera can take a long time if there are many changes to export. (The file checksum now apparently includes some
salt.)
Regarding the yellow vs. green, I'm sorry for the confusion. We tried to make it clear that, simply,
yellow is the new green.
This post explains why we changed it from green to yellow.