[API-users] Get specific occurrences

Hi all, I'm trying to get all the years of occurrence for a specific organism. I tried pagination and with the limit and offset parameters. For example:

http://api.gbif.org/v1/occurrence/search?offset=1&limit=30

But I noticed that each successive page has duplicate results. For example: for the scientific name: Aaptos aaptos, I tried limit= 30 and increased the offset parameter as-

offset=0&limit=30 and offset=1&limit=30

The two queries have 29 common results.

Is this supposed to happen or am I doing something wrong?

Thanks,