# 2018 TDBISAMEngine TableDataTempExtension Duplicating Temporary File Extensions

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I've been playing with the temp table file extensions in version 4.19 and noticed that when I change the TableDataTempExtension value of the Engine component, it adds that extension to all of the temp file names as a part of the temp file name:

30010.dat becomes 30010.tat.tat
30010.idx becomes 30010.tat.idx
30010.blb becomes 30010.tat.blb

Changing the TableIndexTempExtension value does not cause any file name changes.