The polar faces, (001) and (001), of the ferroelectric KTiOPO4 crystal are not equivalent by symmetry. The stability and the growth rate of both faces have been determined by growing thick crystalline layers by liquid phase epitaxy onto oriented crystalline commercial KTiOPO4 slabs. Growth solutions with different molar compositions in the system KTiOPO4-KPO3-KF and different supersaturation degrees end up with the same result. Whereas the (00 (1) over bar) faces are stable under all the experimental conditions used, the (001) ones are not stable and turn into (00 (1) over bar) faces. Head-to-head domains oriented along the [010] axis at vertical bar 7 +/- 1 degrees vertical bar to the [001] axis propagate from the (001) surface of the seed to the as-grown crystalline layers. The final epitaxies obtained by this process show two (00 (1) over bar) polar end faces; so a twin-crystal along the c direction was grown.