Google form adding more than one row every time

I know that when a new response is submitted on Google form, a new row is auto-added to the linked spreadsheet. I use several onformsubmit triggers for my form and linked spreadsheet. But I do not know why more than one row (sometimes more than 100) are being added, which is unnecessary. I have searched Google and Youtube but I think I could not find anything helpful. why is that happening? and how to avoid it?