1. Did you get a hold of her?
2. Did you get hold of her?

Are both the same meaning?

I can only answer for my own usage of these sentences.

"Did you get a hold of her?" asks whether you reached her (by phone, for example), whether you managed to 'contact' her for the purpose of communication -- not physical contact.

"Did you get hold of her?" is unusual, but by analogy with "Did you get hold of it?", it asks if you got into physical contact with her, grasped her with your hand(s) as if to prevent her from falling or from running into traffic, for example.

That said, the use of either of these for either meaning would not disturb me too much.

In Br. E, we say "get hold of her" to mean both, but usually in terms of contacting someone.
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Thank you, CalifJim.
 abbie1948's reply was promoted to an answer.
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Thank you CJ, MHS Boyd.
Both are heard in BrE to mean the same, with the first one probably appearing more in informal contexts.