After being fully vaccinated and boosted; i then got the updated pfizer bivalent covid booster. is it safe to get the moderna bivalent covid booster 2 weeks later? or 2 months later?

Best to stick with what you got first. Check with local CDC guidelines.

There is absolutely no need to get a repeat booster 2 weeks after receiving a booster shot. If you have received one updated booster to cover the omicron variant, there is no reason to get a second at this time. That may change next year, but for now, you should count yourself fully vaccinated.