When taking metronidazole it says take twice a day. i forgot to take my 1 tablet this morning so is it okay to take 2 at same time?

Yes: As usual dosage is three times a day anyway taking 2 at once won't harm you and might help. Though you do not say why you are taking it.

Usually not necessar: Typically you just give the appropriate dose, and don't double it.

Not advisable.: In general, when a medication is twice a day and you forget one dose, you could take it if you remember within 4 hrs of your normal schedule, and then take the next dose at the usual evening time. However, you should not take 2 doses at the same time. Doing so will increase your chances of drug toxicity, or accentuation of side effects, due to higher than therapeutic blood levels.