2x explorer version Z1 is a dual pane file manger. This is from the readme file:

2xExplorer was developed using Visual C++ (utilising MFC classes), single-handedly by Nikos Bozinis in 1999-2002.

2xExplorer is a fusion between the efficient dual-pane file management format of yesteryear and the intuitive tree/content pane format of modern operating systems. It aims to deliver the best of both worlds, without pledging allegiance to either of the two prototypes. You may regard it as an explorer on steroids, with an additional pane for browsing folder contents side to side. Apart for this extra pane, 2xExplorer fills in many glaring omissions in the windows Explorer:

Filters (wildcard based) for limiting the files displayed in a contents pane, and for controlling the selection of items.
Keyboard shortcuts for nearly all commands, an indispensable feature for efficient everyday use.
Briefcase-beating lightweight folder synchronisation engine.
Notepad-thrashing internal simple yet powerful text editor and RTF/Hex viewer.
Improved Find Files tool offering more control over the search criteria.
Printing of folder contents and other statistics.
Automatic Batch file (*.bat) generation that can be used for delicate management operations, as the mass renaming of files.
File and folder shreder (complete destruction).
File split & merge commands.
Create hard links to files and folders (NTFS).
Complete file date information (modified plus created and last accessed) is both shown and used for various operations throughout the program.
Proper sorting for file type using the filename extension alphanumerically; no more ".INI" files before ".BMP" ones like in the confused explorer.

2xExplorer-vZ1