Duplicate symbol的问题

feeling

平台：IBM AIX Version 5
编译器：xlC --- VisualAge C++ Professional / C for AIX Compiler, Version 6
编译时提示信息如下：
ld: 0711-224 WARNING: Duplicate symbol: .memset(void*,int,unsigned long)
ld: 0711-224 WARNING: Duplicate symbol: .memcpy(void*,const void*,unsigned long)
ld: 0711-224 WARNING: Duplicate symbol: .sigset
ld: 0711-224 WARNING: Duplicate symbol: .strncpy(char*,const char*,unsigned long)
ld: 0711-224 WARNING: Duplicate symbol: .strlen(const char*)
ld: 0711-224 WARNING: Duplicate symbol: .strcpy(char*,const char*)
ld: 0711-224 WARNING: Duplicate symbol: .strchr(const char*,int)
ld: 0711-224 WARNING: Duplicate symbol: .strcat(char*,const char*)
ld: 0711-224 WARNING: Duplicate symbol: .ostream:perator<<(ostream&(*)(ostream&)
ld: 0711-224 WARNING: Duplicate symbol: .strcmp(const char*,const char*)
ld: 0711-224 WARNING: Duplicate symbol: .feof(FILE*)
ld: 0711-224 WARNING: Duplicate symbol: .memmove(void*,const void*,unsigned long)
ld: 0711-224 WARNING: Duplicate symbol: .strcmp
ld: 0711-224 WARNING: Duplicate symbol: .strcpy
ld: 0711-224 WARNING: Duplicate symbol: .strncpy
ld: 0711-224 WARNING: Duplicate symbol: .strcat
ld: 0711-224 WARNING: Duplicate symbol: .memmove
ld: 0711-224 WARNING: Duplicate symbol: .bcopy
ld: 0711-224 WARNING: Duplicate symbol: sigset
ld: 0711-224 WARNING: Duplicate symbol: .accept(int,sockaddr*,unsigned long*)
ld: 0711-224 WARNING: Duplicate symbol: .strncmp(const char*,const char*,unsigned long)
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
如果是自己定义的函数、变量，提示“Duplicate symbol”还可以接受，这下它怎么连系统提供的函数都Duplicate symbol呢？
请赐教！