TYPO3 Core

just as a hint.

count comes from class.tx_cms_layout.php =>

function getNonTranslatedTTcontentUids($defLanguageCount, $id, $lP) {
        if ($lP && count($defLanguageCount)) {

            // Select all translations here:
            $queryParts = $this->makeQueryArray('tt_content', $id, 'AND sys_language_uid=' . intval($lP) . ' AND l18n_parent IN (' . implode(',', $defLanguageCount) . ')');
            $result = $GLOBALS['TYPO3_DB']->exec_SELECT_queryArray($queryParts);
...

funny is phpdoc:
Selects across columns, but within in the same PID. Columns are expect to be the same for translations and original but this may be a conceptual error (?)

a workspace overlay is missing IMO here?

How to test: use a current master

1. Create 2 pages, both with translations, both with one translated content element
2. Switch to workspaces
3. Cut 1 content element from one page and paste it into the 2nd page
4. See that at the 2nd page that there are 4 content elements, 2 in default, 2 in translations and still the button "copy default content element"
5. apply patch
6. reload page module of page 2
7. if works, review it

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/9451

Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/9451

Patch set 4 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/9451