6 week Hcg drop, but heartbeat fine??

I’m 6w5d now. This story happened at 6w2d and it has me stumped!

Hcg CRAZY high - 160,000! However, the next day they were 148,000. Still sooo high but had dropped (these samples were processed in two different labs which has me thinking that is the main culprit?)

Ordered an ultrasound for that evening, baby measuring right on time with a strong heartbeat!

So what the heck was up with the Hcg change?! The different labs??

(The blood machine was down the first day and they had to send the samples to a neighboring town)