I am trying to build a network similar to this figure:

Here is the code for training:
import torch
import torchvision
import torch.nn as nn
import numpy as np
import torch.utils.data as data
import torchvision.transforms as transforms
import torchvision.datasets as dsets
from torch.autograd import Variable
import pdb


class RegNet(nn.Module):
  def __init__(self):
    super(RegNet,self).__init__()
    self.Reg_x = nn.Linear(4,4)
    self.Reg_y = nn.Linear(4,3)
    
  def forward(self,x):
    x_x = self.Reg_x(x)
    x_y = self.Reg_y(x)
    return x_x,x_y


# Input
z = Variable(torch.ones(5,4),requires_grad=True)

# Rep Layer
Rep = nn.Linear(4,4)

# Reg Layer
Reg = RegNet()

label_x = Variable(torch.ones(5,4))
label_y = Variable(torch.zeros(5,3))

criterion = nn.MSELoss()
optimizer1 = torch.optim.SGD(Rep.parameters(), lr=0.01)
optimizer2 = torch.optim.SGD(Reg.parameters(), lr=0.01)

# train
# feed-forward
rep_out = Rep(z)
pred_x,pred_y = Reg(rep_out)

loss_x = criterion(pred_x,label_x)
loss_y = criterion(pred_y,label_y)
loss = loss_x + loss_y

loss.backward()

I have a similar implementation in Torch. On comparing the performance, the predictions pred_y are consistent with Torch implementation while pred_x is way off. Is there something not correct in my implementation.