X1 = (1200,40,1)
y1 = (1200,10)

model = Sequential()
model.add(LSTM(12, input_shape=(40, 1), return_sequences=True))
model.add(LSTM(12, return_sequences=True))
model.add(LSTM(6, return_sequences=False))
model.add((Dense(10)))

X2 = (1200,40,1)
y2 = (1200,40)

X_stack = (1200,40,2)
y_stack = (1200,40,2)

model = Sequential()
model.add(LSTM(12, input_shape=(40, 2), return_sequences=True))
model.add(LSTM(12, return_sequences=True))
model.add(LSTM(6, return_sequences=False))
model.add((Dense((10,2))))