I could understand your concern in modern times however, Thomas and Hannah had at least nine (possibly ten) children between 1825 and 1840. They were all baptised at All Saints, with father Thomas described as a Gun Flint Maker. The possible tenth is one baptised to Thomas and Ann but, again he is a Gun Flint Maker.
They were as follows
1824 Apr 9 Thomas William S of Thomas & Hannah SIMMONS Maidstone, Gun Flint Maker
1825 Oct 2 Agnes D of Thomas & Hannah SIMMONDS Maidstone, Gun Flint Maker
1826 Aug 23 John George S of Thomas & Hannah SIMMONDS Maidstone (Flint Maker)
1828 May 30 James Benjamin S of Thomas & Hannah SIMMONDS Maidstone (Gunmaker)
1830 May 5 Agnes Amelia D of Thomas & Hannah SIMMONS Maidstone (Gun Flint Maker)
1835 Jul 12 Phyllis Lydia Woodger D of Thomas & Hannah SIMMONDS Maidstone, Gun Flint Maker
1836 Apr 10 Agnes Sophia D of Thomas & Hannah SIMMONDS Maidstone, Gunflint Maker
1838 Mar 25 Sophia Selina D/o Thomas & Hannah SIMMONDS GunFlint maker, otp
1840 May 27 William Henry S/o Thomas & Hannah SIMMONS Gunflint maker,otp
Possible tenth
1835 Mar 15 Sophia D of Thomas & Ann SIMMONDS Maidstone, Gun Flint maker
All from a Transcription.
If you are still concerned about Hannah's maiden name, I can only suggest, you purchase the Birth Certificate of one of the last two children say Sophia Selina Maidstone District March 1838 Vol 5 Page 294.
I do hope this enables you to move forward, or should I say backwards.
Tony