HI,
I have tested this and what I found that Worksheet id for the first sheet is always "od6" (by default).
When you will add more worksheets into the same spreadsheet, then worksheet id will be generated randomly. This is the reason you are getting different worksheet id.
This is because if you are having different worksheets in one spreadsheet then you need to have different worksheet_id to map(pull) the data on specific worksheet.
Note: Their might be the scenario where you have created a multiple worksheet in the spreadsheet. After that deleted first one, it shows you a different worksheet_id.
Thanks & Regards,
Shobhit Tripathi
Fujitsu RunMyProcess