It does still mean the same thing.
가 is used additionally. As you might know, when you're talking about a subject using 있다/없다 you can add (or not) the subject marker 이/가. e.g. 시험 있다/시험이 없다. Either the way, the message is understood in the same way.
Because this grammar you are learning now contains 있다/없다, you can add or not 이/가 before the verb.
I hope it helps..