Making outputs of sub-models the inputs of other models LSTM
Try removing the Input layer

hidden_1_2 = LSTM(300,return_sequences = True)(merge)
hidden_1_3 = Dropout(0.5)(hidden_1_2)
hidden_1_4 = LSTM(200,return_sequences = False)(hidden_1_3)
hidden_1_5 = Dropout(0.5)(hidden_1_4)
hidden_1_6 = Dense(100,kernel_initializer='uniform',activation='relu')(hidden_1_5)
hidden_1_7 = Dense(1,kernel_initializer='uniform',activation='relu')(hidden_1_6)