The complete reaction is like this
Stage I CaCO3+ 2 HCl = CaCl2 +H2CO3
Stage II H2CO3 = H2O + CO2
Calcium Carbonate reacts wit Hydrochloric acid to form Calcium Chloride and Carbonic Acid.
Carbonic Acid is unstable and it breaks down to Water and carbon Dioxide gas which escapes in the atmosphere.
So H2O and CO2 don’t make H2CO3 again because it is less stable