请问一下输入ssc install metan之后出现了下面的r（602），是为什么呢？怎么才能成功安装metan呢？ 谢谢

. ssc install metan checking metan consistency and verifying not already installed...

the following files already exist and are different:     /Users/zhangqi/Library/Application Support/Stata/ado/plus/m/metan.ado     /Users/zhangqi/Library/Application Support/Stata/ado/plus/m/metan.hlp     /Users/zhangqi/Library/Application Support/Stata/ado/plus/l/labbe.hlp

no files installed or copied (no action taken) r(602);