I got the same exception but there are not exist the same name sheet.
Interesting and there are two sheet in workbook A,named 'Sheet999' and 'Travel',one of this sheet 'Sheet999' can be copy to another workbook correctly ,but the other one has throw the exception.(An item with the same key has already been added)
And i give the example code here :
( http://www.liuzhiyong2012.cn/dl/ClosedXML_0626.rar )
Interesting and there are two sheet in workbook A,named 'Sheet999' and 'Travel',one of this sheet 'Sheet999' can be copy to another workbook correctly ,but the other one has throw the exception.(An item with the same key has already been added)
And i give the example code here :
( http://www.liuzhiyong2012.cn/dl/ClosedXML_0626.rar )