请问Interface的Matching Option到底是什么意思？

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HELP文件中如下描述：
1  When the Matching option is selected, ANSYS Fluent checks if one interface zone sits on top of the other and displays messages if there is an overlap of cell zones that are connected through a mesh interface (therefore making the interface invalid for use).
为什么开启Matching option后，通过mesh interface连接的网格如果重叠，会导致interface invalid for use？
2  for non-matching interfaces:
Info: Interface zones overlap for mesh interface. This could adversely affect your solution.
对于不匹配的界面，Interface zones重叠会导致不良解。
3  for matching interfaces:
Warning: Interface zone overlaps for mesh interface ，This could generate left-handed faces on the interface and make it invalid for use.
对于匹配的界面，Interface zone overlaps会产生左手面。

fluid-fluid匹配的Interface zone的重叠部分不是应该生成interior，为什么开启Matching option反而会产生left-handed face？是我对HELP的理解出错了吗，求解..