DLL function(s) problem

[silur]

Simple question i have this code in an EXE:

void foo(int var1);
void foo(int var1,int var2);

void foo(int var1);
void foo(int var1,int var2);

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so i can use both with the same name
how can i use this in a DLL my Qt compiler says that the 2 function confilts