ValueError: Attempt to have a second RNNCell use the weights of a variable scope that already has weights
You can trying to add scope='lstmrnn' in your tf.nn.dynamic_rnn() function.
I run ptb_word_lm.py provided by Tensorflow 1.0, but it shows this message:

ValueError: Attempt to have a second RNNCell use the weights of a variable scope that already has weights:
  'Model/RNN/multi_rnn_cell/cell_0/basic_lstm_cell'; and the cell was
  not constructed as BasicLSTMCell(..., reuse=True).  To share the
  weights of an RNNCell, simply reuse it in your second calculation, or
  create a new one with the argument reuse=True.

Then I modify the code, add 'reuse=True' to BasicLSTMCell, but it show this message:

ValueError: Variable Model/RNN/multi_rnn_cell/cell_0/basic_lstm_cell/weights does not
  exist, or was not created with tf.get_variable(). Did you mean to set
  reuse=None in VarScope?

How could I solve this problems?