If the rescue dog experienced abuse, it's a good idea to change their name because there can be relatively permanent negative associations with it. If she likes her name, I see no reason to change it. If she seems skittish, I might try changing it to something else different sounding, perhaps with an 'oh' ending.  

I am agreeing with Webby ( HAVE to agree with Webby LOL) and Tali.. I think it's the tone of voice and the reaction to response..

If you like the name Ruby,... so will she!!

We had no idea what Sofia's name was before we got her, and she was responding to "Sofia" within a few days.. Of course now, she'd prefer "Your most gracious and royal majesty" but it too long for immediate recall.. LOL

Sometimes the rescue will change the name. Sometimes there is a name change because they don't know what name the dog had before (as in strays).

I recently transported a 4 year old rescue female whose owner had died. There were six dogs at the home and when the husband died, the widow could not take care of them, so the turned them over to a "rescue". The quotation marks are because the person passed herself off as a rescue (she has operated under numerous names) but in fact just moved them to some old kennels on a piece of property that she neither owned nor leased and had no rights to use. There was no shelter, and no one around. She had someone that was supposed to come by and feed them "three times a week", but in fact it was more like once a week. After about three weeks in these conditions, the five Dobermans were rescued by a real licensed rescue organization - Doberman Rescue Alliance of Florida. (Unfortunately, before they were alerted, a non-Doberman, the sixth dog died of starvation. Google the article named Scruffy never got his second chance for the story.)

The one I transported was originally called Gail, but her name was changed to Gabrielle, but was called Gabby by everyone. Most states require registration of the rescues, I was surprised by the paperwork that had to accompany Gabby, including a Georgia form and a Federal interstate form (her forever home was in Florida).

Of the five Dobermans rescued from that situation, all five have been adopted, and three of them had their names changed while in rescue.

If the name they arrive with is one that is okay with you, don't change it. If it does not seem to fit, or if you want to call them something else, it will be okay with them to. They are intelligent and will figure out you are talking to them very quickly.