I got multiple entry coming back from Canada

I went to Canada for landing. I didn't apply for new H-1B visa during the trip. when I came back, I was requried to fill out new I-94 card. The officer at the airport wrote down "Multiple entry" on the new I-94 card. I don't think it is really useful though, for example, if I leave for China, I will need to give it back. I still need to apply for a new visa stamp to come back in.