Problem in adding multiple Python modules to ModuleManager

I have been observing intermittent errors with Python modules like IndexError: map::at with mod.change_input() when I have more than one Python module in the module manager. The problem never happens if I have only one Python module, but happens randomly if I have more than one. I think the code below shows the root of the problem.

import pluginplay as pp
from py_test_pluginplay import OneInOneOut, OneIn, OneOut

ptype = OneInOneOut()
class test_module(pp.ModuleBase):
    """Basic PluginPlay module that satisfies OneInOneOut property type"""
    def __init__(self):
        pp.ModuleBase.__init__(self)
        self.description(self.__doc__)
        self.satisfies_property_type(ptype)

    def run_(self, inputs, submods):
        s, = ptype.unwrap_inputs(inputs)
        r = self.results()
        return ptype.wrap_results(r, s)

ptype = OneIn()
class test_module2(pp.ModuleBase):
    """Basic PluginPlay module that satisfies OneIn property type"""
    def __init__(self):
        pp.ModuleBase.__init__(self)
        self.description(self.__doc__)
        self.satisfies_property_type(ptype)

    def run_(self, inputs, submods):
        s, = ptype.unwrap_inputs(inputs)
        r = self.results()
        return ptype.wrap_results(r, s)
ptype = OneOut()
class test_module3(pp.ModuleBase):
    def __init__(self):
        pp.ModuleBase.__init__(self)
        self.satisfies_property_type(ptype)
        self.add_input('inp2')

    def run_(self, inputs, submods):
        r = self.results()
        return ptype.wrap_results(r)

mm = pp.ModuleManager()
mm.add_module('test_module', test_module())
mm.add_module('test_module2', test_module2())
mm.add_module('test_module3', test_module3())
for key in mm.keys():
    print(key, mm[key])
print(mm['test_module'] == mm['test_module2'])
print(mm.at('test_module') == mm.at('test_module2'))

If you run the Python code above several times, you will get something like:

(nwx) 01:15:00|nwx|test> python mm_test3.py
test_module <pluginplay.Module object at 0x7fafa0d2a330>
test_module2 <pluginplay.Module object at 0x7fafa0d24a70>
test_module3 <pluginplay.Module object at 0x7fafa0d1d970>
True
True
(nwx) 01:15:02|nwx|test> python mm_test3.py
test_module <pluginplay.Module object at 0x7f290c631530>
test_module2 <pluginplay.Module object at 0x7f290c631530>
test_module3 <pluginplay.Module object at 0x7f290c631530>
True
True

Somehow in the second run, test_modules that satisfy different property types are stored at the same memory location. Module comparison always returns True might be because the comparison operator not being exported, but I think main issue is that Python modules are not added to the module manager properly. Maybe this issue is related to #309 somehow.

The report names ModuleManager, ModuleBase, and mod.change_input; first reproduce the supplied Python script repeatedly, then inspect the ModuleManager add_module/at path and related Python binding behavior, including issue #309. Done means distinct modules remain distinct across runs and the intermittent IndexError no longer occurs, with a regression test for multiple Python modules.