If you use this medication at the same dosage more than once a day, then just add the two quantities together and enter the drug/dosage once in your drug list. If morning is a different strength (dosage) than evening, for example, then change the dosage/quantity and click the "Add drug and dosage" again. You will have the same drug added to your "Drug List" a second time - with the new dosage. Note, the same exact drug & dosage cannot be in the drug list more than once. The drug will be entered at the bottom of your list so you may need to scroll down if your medication list is long to see the addition of the drug.
Try to choose the dosages that best describe your actual life. If you purchase 500mg pills and cut them in half because your prescription actually calls for 250mg two times a day, then choose 500mg tablets with a quantity of 30 per month — instead of 250mg tablets at 60 per month. Remember, you are trying to reflect your purchases of the medications, not your actual taking of the medications. So there is no way to enter "taken as needed" instead ask yourself how often you purchase this medication. "Take as needed" could mean 3 times per day or it could also mean once every other month. Your purchase pattern leads to a much more accurate Medicare plan comparison.