As purespirit said, spirit guides never abandon your or leave you alone. All they can do is to see if their job with you is done or not, and if they taught you and gave you the values they wanted to grant you from the first place. If you have listened to them, let them to teach you, guide you and advice you, they can know that their job is done and that they managed to accomplish what they wanted (in your case, the accomplishment was to guide you, teach you and give you advices).
But the guides never leave you, even if their job is done and even if you got to know all the material and values they taught you. Your spirit guide will always be with you and see how you're doing. It will always guide in in your unique path, watch you, get you to the right directions, give you different advices about your path, and always light you way and advise you to do whatever is best for you.
Even if for now you spirit guide's job is done, you will always need some guidance, advices, lessons to life, etc. There is always an opportunity of getting a good lesson.
What I am saying is that for now, you may not need to much teaching or advices, but when you will be ready to be taught and guided again, or when you will really need it and your spirit guide notices that there's something to do, it will keep guiding you, giving you advices, teaching you and getting you to the best and safest directions.
As for the question itself, you can certainly have more than one spirit guide while being in your spiritual path. You don't have to stick around with a single spirit guide during you spiritual path and journey. I myself had a lot of spirit guides, not all of them were good or qualified, some of them were even a bit 'nasty'.
Spirit guides are all around, thus you will have more than one in your spiritual path if you choose to. It's only up to you to decide if you're ready to be guided by more than one spirit guide in your spiritual path / journey.
For an instance, if you have more than only one teacher at school, you can have more than a single spirit guide :)
Oh, and to make it clear, even if the spirit guides do not tend to leave, you can choose if to keep being guided by them or not.
If you let one of the guides go, you can obviously be guided by another one.
Hope it helps,