You didn't say what technique you are using to not display the numbers for Heading1, and that might make a difference, but try this:

Don't turn off the display of numbers for Heading1 until Heading2 is working.
Right-click on Heading1 in sec1 and set numbering to none. Do the same for Heading1 in sec2.

Heading2 should be numbered correctly now. Again, I don't know how you turned off the display of numbers in Heading1, but if that technique doesn't work, you can modify the style so the font color of the number is white.

Or, you can leave what you have now but make a new style that looks like Heading1 and set those in the first 2 secs to the new style.