Position Object doesn't birth any particles...it takes existing particles and scatters them. For example, if you birth 10000 particles and then use Position Object to scatter them on 20 vertices, you'll get 500 particles per vert.
If you just want 1 particle per element (vert, face, etc), use Birth Surface instead.
If you just want 1 particle per element (vert, face, etc), use Birth Surface instead.