delete duplicate translation keys

Remove duplicate Russian translations

before the following error: 
An exception has been thrown during the rendering of a template ("[ERROR 94] Validation failed: no DTD found ! (in n/a - line 2, column 21)
[ERROR 1877] Element '{urn:oasis:names:tc:xliff:document:1.2}trans-unit': Duplicate key-sequence ['form.label_firstname'] in key identity-constraint '{urn:oasis:names:tc:xliff:document:1.2}K_unit_id'. (in /private/var/www/history/web/ - line 365, column 0)
[ERROR 1877] Element '{urn:oasis:names:tc:xliff:document:1.2}trans-unit': Duplicate key-sequence ['form.label_lastname'] in key identity-constraint '{urn:oasis:names:tc:xliff:document:1.2}K_unit_id'. (in /private/var/www/history/web/ - line 369, column 0)") in ArmdEventBundle:Event:tapeTime.html.twig at line 4.