Some pdftk users process hundreds of files. Performing this work on a Windows machine can yield unexpected results. The problem arises from the Windows command-prompt shell, not pdftk. The problem arises because for every long filename, Windows creates a short, DOS-compatible (8.3) alias filename. This short alias filename might end up matching a wildcard expression, even when the long filename does not. When using pdftk, the result is that you end up with more input files than you wanted.
This article offers a couple workarounds and then describes the case where this problem arose.
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