The words damming sound the same but have different meanings and spellings. Why do damming sound the same even though they are completely different words?
The answer is simple: damming are homophones of the English language.
That condemns or exposes to condemnation or damnation: as, <em>damning</em> proof; <em>damning</em> criticism.
That damns; damnable.
Present participle of <xref>damn</xref>.
Property which <xref>damns</xref>.
Definitions from The Century Dictionary., from the GNU version of the Collaborative International Dictionary of English., from Wiktionary, Creative Commons Attribution/Share-Alike License. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").