Two QNodes execution error

Hi PennyLane team!

I am trying to execute two QNodes at the same time but something goes wrong:

import pennylane as qml

dev = qml.device("default.qubit", wires=2)

@qml.qnode(dev)
def circuit1(x, y):
    qml.Hadamard(0)
    qml.RX(x, wires=0)
    qml.RY(y, wires=1)
    qml.CNOT(wires=[0, 1])
    return qml.expval(qml.PauliZ(0))

@qml.qnode(dev)
def circuit2(x, y):
    qml.RX(x, wires=0)
    qml.RY(y, wires=0)
    return qml.expval(qml.PauliY(0)), qml.probs(wires=[0,1])

qnodes = qml.QNodeCollection([circuit1, circuit2])

qnodes(0.5643, -0.45)
~/pennylane/pennylane/collections/qnode_collection.py in convert_results(results, interface)
    269             from autograd import numpy as np
    270 
--> 271             return np.stack(results)
    272 
    273         return results

~/autograd/autograd/numpy/numpy_wrapper.py in stack(arrays, axis)
     92     shapes = set(arr.shape for arr in arrays)
     93     if len(shapes) != 1:
---> 94         raise ValueError('all input arrays must have the same shape')
     95 
     96     result_ndim = arrays[0].ndim + 1

ValueError: all input arrays must have the same shape

Please help me, what is the issue here?