I might have taken a 2nd 40mg omeprazole 2 hours after my usual dose. i don't feel different, but should i skip a day to be safe?

No: Depending on the condition the maximum dose is 80-120mg per day. http://nzf.org.nz/nzf_771 So potentially 80mg shouldn't be a big problem and should be ok to take your usual dose tomorrow. You can have a look at the above link it will give you a list of adverse effects etc If in doubt consultation with a pharmacist or doctor licensed in your area is recommended.

No,: stay on schedule, no harm done, it will get off your system in less than a day, good luck