I believe that taking both these skills is a waste of thief points, but I ask then why would they create two similar skillls?
Isn't "silently and covertly' the same as 'without coming out of hiding'?
COVERT (2185)

Syntax: Automatic skill

Some thieves have learned to open and close both doors and containers silently
and covertly.



IMPROVED HIDE (1421)

Syntax: Automatic Skill

This additional training in the art of hiding allows thieves to do more while
remaining in the shadows. For example, thieves with this level of skill have
been known to communicate with others and to open and close doors without
coming out of hiding.