Comments Pagination Incorrect

If I have a criteria of:

            var criteria = new CompositeCriteria<CommentFilter, CommentsExtensionModel>
                           {
                               Filter = new CommentFilter { Ancestor = ancestralComment },
                               PageInfo = new PageInfo { PageSize = 2, PageOffset = 0, CalculateTotalCount = true},
                               OrderBy = { new SortInfo(CommentSortFields.Created, true) }
                           };

Call the service:

var results = _commentService.Get(criteria)

It works, no issues, 2 Results, Total Matching 5.

And as an example lets say it returns

results.Results[0].Data.Id = 123

results.Results[1].Data.Id = 456

All fine.

Now if I paginate:

            var criteria = new CompositeCriteria<CommentFilter, CommentsExtensionModel>
                           {
                               Filter = new CommentFilter { Ancestor = ancestralComment },
                               PageInfo = new PageInfo { PageSize = 2, PageOffset = 1, CalculateTotalCount = true},
                               OrderBy = { new SortInfo(CommentSortFields.Created, true) }
                           };

Again I get 2 more results, but the issue I am seeing is that:

results.Results[0].Data.Id = 456

results.Results[1].Data.Id = 789

As you can see the results returned after the pagination includes the last previous result.

Is this by design or is this a bug?

Thanks