1. and 2. are both correct, and mean that the speaker does not wish to interrupt or otherwise separate the two people spoken to.
3. Correct, because it is the same as (1). 'The' because it is a single, specific set of 'two', the two people spoken to.
4. is incorrect for the same reason. There is only one set of 'two'.
5. is incorrect for the same reason. No article means it must be plural-- more than just the two people ('you's) spoken to.
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