Before you can begin playing hymns or Odes at the organ you need to know that, when in the same voice there are 2 notes the same, the first one loses one half of its value [See blog, Hymns, Part IV].
These 4 quarter notes (photo) would be executed by playing the first 3 quarter notes as 8th notes each followed by an 8th rest, then holding the 4th quarter note its full value.
On the piano, repeated notes can be held their full value because the hammer drops back and the sound decays immediately.
On the organ, all you have is a pipe with air moving in it for as long as you hold down the key.
Therefore, in order to hear the repeated notes clearly at the organ, you have to cheat; you have to exaggerate their release.
For the same reason, if the first of 2 notes repeated in the same voice happens to be dotted, that first note loses the value of the dot.