No. There's no law or rule that says you have to file your 2017 return before you can do your 2018 return. However, it's best to prepare your 2017 return first, if possible.
If you do your 2018 tax return and you're getting a refund, you'll most likely get your 2018 refund even if you didn't file your 2017 tax return. Each year stands alone.
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