Creating a view with "Bookmark: favorites Marked Time" sort criteria will list a node more than once

This isn't a bug. A node may be bookmarked by several users, so the node (the record) repeats itself for each bookmarking user. You'll understand the rationale if you switch to the Table, or List, style and add the '... Marked Time' field.

But I see that the description says "Sort by the time a node was last bookmarked using [...]" and this is indeed misleading.

Add the 'Node: Distinct' filter. I believe that, because of the sort, the database will indeed pick the "last bookmarked" record. Let us know if your problem was solved.

(BTW, you'd better use the 'dev' version, not the '1.4' one.)

I've checked this issue further.

It turns out 'Node: Distinct' has no effect in this case.

Have you considered sorting by 'Node: Updated Time' instead?
Or, enable the built-in 'statistics' module and sort by 'Node: Total Hits'.

perhaps in a later version, that should be an included criteria?

That would entail recording the 'last bookmarked' timestamp somewhere. We could follow Drupal's {node_comment_statistics} example and store this information in our{views_bookmark_node_count} table (after renaming it to {views_bookmark_node_statistics}).

And since sorting by 'last time bookmarked' would be different than sorting by 'time bookmarked', we will have to have two sets of sorts/fields, something which will confuse the admin.

But the problem isn't technical. The problem is of essence: I don't see why this feature is useful. I had a somewhat positive opinion of this feature when I started typing this reply, but the more I think of it the more useless this feature seems to me. I guess you have a 'Posts popularity' view and you want to sort all those nodes bookmarked by '1 users'. There are several reason why 'last bookmaked time' doens't have a tangible advantage over the alternatives I suggested above. I'm trying to think of other, useful use-cases for this feature, but I don't see any.

If the "marked time" doesn't do as the description says...

(I shell fix this as soon as some other patch gets in.)

But the problem isn't technical. The problem is of essence: I don't see why this feature is useful.

So this part is "won't fix". If anybody thinks otherwise he may reopen this issue.

But I see that the description says "Sort by the time a node was last bookmarked using [...]" and this is indeed misleading.

I fixed that (simply removed the word 'last'.)