Why were two galaxies named "The Sagittarius Galaxy"? Is this common? Phys.org's  says:


  The formation of the Sun, the Solar System and the subsequent emergence of life on Earth may be a consequence of a collision between our galaxy, the Milky Way, and a smaller galaxy called Sagittarius, discovered in the 1990s to be orbiting our galactic home.


and I checked Wikipedia which says:


  Sagittarius Dwarf Irregular Galaxy Not to be confused with Sagittarius Dwarf Spheroidal Galaxy.


and 


  Sagittarius Dwarf Spheroidal Galaxy Not to be confused with Sagittarius Dwarf Irregular Galaxy.


Question: But my question is how did they both get named after a very well known constellation? Is it common to name galaxies after constellations? Do many constellations have namesake galaxies?




  The Sagittarius dwarf galaxy has been orbiting the Milky Way for billions for years. As its orbit around the 10 000 more massive Milky Way gradually tightened, it started colliding with our galaxy's disc. The three known collisions between Sagittarius and the Milky Way have, according to a new study, triggered major star formation episodes, one of which may have given rise to the Solar System.  Credit: European Space Agency


Screen shot from the ESA video Dwarf galaxy collisions make stars form in Milky Way
In addition to the Andromeda Galaxy (M31)
and the Triangulum Galaxy (M33),
the Local Group includes several dwarf galaxies named after the constellations in which they appear.
In most cases, nearby dwarf galaxies in the same constellation are distinguished by a letter or Roman numeral suffix.