Is it safe to use your diabetic needle twice when your injecting two different insulin's at the same time?

Not recommended. Once the needle goes through your skin, two things happen. First , it gets dull. Little bits of metal stick out, so the needle causes more pain with later injections, and the metal bits can break off under the skin causing soreness. Additionally, the needle can pick up bacteria from the skin, and when you insert the needle into the Insulin vial, contaminate the Insulin with bacteria.
NO! Reusing needles is associated with infections which may cause severe disease from the introduction of skin bacteria into the body by virtue of no longer using a sterile needle. Additionally, you would be introducing the bacteria into the next Insulin vial which would compound your risk for infection.
No. You run the possibility of contaminating the second bottle with Insulin from the first bottle. Speak to your doctor about the possibility of using one of the many combination Insulin preparations on the market.