Very strange errors while using cout in module file - c++

Question

Sorry, I couldn't make an MRE, the error doesn't happen in the cut code, but I will cut the code as much as possible.
main.cpp
#include <iostream>
#include "Functions.h"
using namespace std;
import TNode;
//USE C++20
int main()
{
string line;
cout << "Enter line:\n";
getline(cin, line);
TNode<char> head = stringToBinaryTree(line);
line;
}
Functions.h
#pragma once
#include <string>
using namespace std;
import TNode;
TNode<char> stringToBinaryTree(string s);
Functions.cpp
#include "Functions.h"
using namespace std;
TNode<char> stringToBinaryTree(string s) {
if (s.size() == 0) return TNode<char>();
TNode<char> result(s[0]);
for (size_t i = 1; i < s.length(); i++)
{
result.addChildren(s[i]);
}
return result;
}
TNode.ixx (cut)
module;
#include <iostream>
export module TNode;
export{
template <class T> class TNode;
}
using namespace std;
template <class T>
class TNode {
T value;
TNode<T>* leftChildren;
TNode<T>* rightChildren;
TNode<T>* Parent;
public:
TNode();
TNode(const T value);
TNode(TNode<T>& parent, const T value);
TNode(const TNode<T>& copyTree);
TNode<T>& operator=(const TNode<T>& source);
TNode<T>* addChildren(T value);
TNode<T>* left() const;
TNode<T>* right() const;
TNode<T>* parent() const;
T getValue() const;
void setValue(T value);
};
//then only the used methods and functions
template <class T> TNode<T>::TNode(TNode<T>& parentNode, const T value) {
this->value = value;
leftChildren = nullptr;
rightChildren = nullptr;
Parent = nullptr;
if (parentNode.getValue() >= value) {
if (parentNode.right() != nullptr) TNode(*parentNode.right(), value);
else {
parentNode.rightChildren = this;
Parent = &parentNode;
}
}
else {
if (parentNode.left() != nullptr) TNode(*parentNode.left(), value);
else {
parentNode.leftChildren = this;
Parent = &parentNode;
}
}
}
template <class T> TNode<T>* TNode<T>::addChildren(T value) {
TNode<T>* children = new TNode<T>(*this, value);
return children;
}
template <class T> void recursionCopy(TNode<T>* dest, const TNode<T>* source) {
dest->addChildren(source->getValue());
//cout << "Added " << source->getValue() << "to destination"; //if uncomment this happens error C2995 and C2572
//if (dest->parent()) cout << " with parrent " << dest->parent() << "\n"; //but if uncomment this while still have prev line uncommented its LNK2005 and LNK1169 errors now
//else cout << "\n";
if (source->left()) {
//cout << "Goind to left with value " << source->left()->getValue() << "\n";
recursionCopy(dest, source->left());
}
if (source->right()) {
//cout << "Goind to right with value " << source->right()->getValue() << "\n";
recursionCopy(dest, source->right());
}
}
template <class T> TNode<T>::TNode(const TNode<T>& copyTree) {
value = copyTree.value;
recursionCopy(this, &copyTree);
}
template <class T> T TNode<T>::getValue() const {
return value;
}
template <class T> TNode<T>* TNode<T>::parent() const {
return Parent;
}
The problem happens in the recursionCopy() function.
When I don't uncomment the cout code, there are no compilation or link errors.
When I uncomment the first line where I used getValue(), the compiler is getting MAD and saying the operator!= template is already defined. Why? I am not defining or using operator!=, but it gives me this error from the <iosfwd> file.
But the interesting part comes when I uncomment the second line with parent(), it causes linker errors with 8 functions, but in Functions.obj for some reason. Here one of the linker errors:
"public: void __thiscall std::basic_ostream<char,struct std::char_traits<char> >::_Osfx(void)" (?_Osfx#?$basic_ostream#DU?$char_traits#D#std###std##QAEXXZ)" already defined in Functions.obj