"An item with the same key has already been added"

excel

#1

Im trying to make a stable loop which read the range in one worksheet in excel and appends this as a new sheet in another book.

about half of the times I get the error in topic, which after I have a tab added, but no data in it.
the other half of times I have no problem with the workflow.

Anyone that is familiar with the problem?

In a loop i use:
Read Range & Append Range