Two near-identical scripts cause a cat to jump in different ways - why?

The first cat repeatedly jumps a decent distance on input, the second makes small hops repeatedly when the button is held. I've stared at the code for ages, but can't see the critical difference. Can I get fresh eyes?

I'm using a version of the sample code found here to move my two cat characters around the environment. I'm in the process of separating the interface and movement code (good practice, I hear).

My original code (currently controlling the first cat) looks like this (this gives desired jumping behavior):

 using UnityEngine;
 using System.Collections;
 
 public class CatControlP1Red : MonoBehaviour {
     public    float         speed             = 6.0F;
     public    float         jumpSpeed         = 8.0F;
     public    float         gravity         = 20.0F;
     private Vector3     moveDirection     = Vector3.zero;
     public    Transform     catRotate;
 
     void Update() {
         CharacterController controller = GetComponent<CharacterController>();
         if (controller.isGrounded) {
             moveDirection = new Vector3(Input.GetAxis("L_XAxis_1"), 0, Input.GetAxis("L_YAxis_1"));
 
             moveDirection = transform.TransformDirection(moveDirection);
             if(moveDirection != Vector3.zero)Rotate (moveDirection);
             moveDirection *= speed;
             if (Input.GetButton("A_1"))    moveDirection.y = jumpSpeed;    
         }
         moveDirection.y -= gravity * Time.deltaTime;
         controller.Move(moveDirection * Time.deltaTime);
     }
 
     void Rotate(Vector3 catTarget){
 
         Quaternion rotation = Quaternion.LookRotation(catTarget);
         catRotate.rotation = rotation;
 
     }
 }
 

...while the code controlling the second cat (two scripts, CatControlP2Blu and CatMove) looks like this(this gives undesired hopping behavior):

 using UnityEngine;
 using System.Collections;
 
 public class CatControlP2Blu : MonoBehaviour {
     private    CatMove        catMove;
 
     void Awake () {
         catMove                 = GetComponent<CatMove> ();
     }
 
     void Update() {
         Vector3 moveDirection     = new Vector3(Input.GetAxis("L_XAxis_2"), 0, Input.GetAxis("L_YAxis_2"));
         bool    jump            = Input.GetButton("A_2");
         catMove.MoveCat(moveDirection, jump);
     }
 }
 

...and this:

 using UnityEngine;
 using System.Collections;
 
 public class CatMove : MonoBehaviour {
 
     public     Transform     catRotate;
     public     float         speed             = 6.0F;
     public     float         jumpSpeed         = 8.0F;
     public     float         gravity         = 20.0F;
 
     public    void MoveCat (Vector3 moveDirection, bool jump) {
         CharacterController controller = GetComponent<CharacterController>();
         if (controller.isGrounded) {
 
 
             moveDirection = transform.TransformDirection(moveDirection);
             if(moveDirection != Vector3.zero)Rotate (moveDirection);
             moveDirection *= speed;
             if (jump)    moveDirection.y = jumpSpeed;
         }
         moveDirection.y -= gravity * Time.deltaTime;
         controller.Move(moveDirection * Time.deltaTime);
     }
 
     void Rotate(Vector3 catTarget){
         
         Quaternion rotation = Quaternion.LookRotation(catTarget);
         catRotate.rotation = rotation;
         
     }
 }

I've sat the two methodologies beside each other in-editor (Sublime) and I cannot see why the first jumps normally and the second barely hops for life of me.

What am I not seeing? Many thanks in advance.

--Rev

EDIT: A further description of the current observed behavior...

Using the code above, unchanged but for replacing GetButton with GetButtonDown (to eliminate hopping),

The entirety of Cat1's jump lasts approx. 0.73 seconds and takes it approx a meter and a half off the ground.

The entirety of Cat2's jump lasts approx. 0.28 seconds and takes it approx 15-20 cm off the ground.

FURTHER EDIT: Red (First Cat, desired behavior, jump input is highlighted):

Blu (Second cat, undesired behavior, jump input is highlighted)