Message
(TSK) ERROR: TSK.bck file already seems to exist a previous run may not have been finished cleanly file .TSK possibly corrupted job finished with error(s)
Example
File name = SAPAPPL2_1.TSK.bck and SAPAPPL2_1.TSK
Solve
Run R3load for merge file then rerun sapinst or R3setup
Logon <sidadm>
->go to install/export/import directory from sapinst or R3setup
->run R3load to merge TSK and TSK.bck file
# Case Export heterogeneous with command file
R3load -merge_bck -e SAPAPPL2_1.cmd
# Case Import heterogeneous with command file