first off you can always inject way more air than your going to draw, it doesn't matter..draw your 1cc of deca, remove from bottle, pull back on syringe to the 3cc point, keep needle pointed up, inject the 2cc of air into the test bottle and draw your 1cc of test. When injecting the 2cc of air into the second bottle just stop short of letting the deca in the syringe make it to the needle. If you were ever to push hard and inject a little deca into your test bottle it doesn't make any difference anyway, it's no big deal.
Run, Run, Run, the postal inspector is at your door!