Hi
It is OK; life happens.
Like with all meds you have to give twice daily, you ideally keep the gap as close to 12 hours as possible under the circumstances, whether that is by moving the dosage forward or back. Once you get to a less than a 4-6 hours gap, consider skipping it altogether and only go with the single dose on the day to avoid overdosing on a double dose. Giving double once a day doesn't prolong the time the medication is working in the body, if that makes sense to you?
The same goes for human medication like antibiotics, painkiller etc. where maintaining a steady supply is key to treatment and double doses are not recommended. You can usually find similar advice on the medical leaflet that comes with your own tablets.