When a virtual service is deployed, VSname.mar file and VSname.mar.tracking folder are created automatically in DevTest_Home/vseDeploy/VSE_2013 folder and these are deleted when VS is removed in the VSE console. Another folder is also created in lisatmp_x.x.x/lads folder, which will have the VS details. lisatmp_x.x.x refers to lisatmp_VersionOfDevTest.
You can copy just the VSname.mar files for your backup purposes and tracking folder will be created automatically when you copy the VSname.mar files to DevTest_Home/vseDeploy/VSE_2013 folder.
When you copy the VSname.mar files to DevTest_Home/vseDeploy/VSE_2013 folder a new folder is also created in lisatmp_xxx/lads folder with the updated VS details.
Documentation doesn't refer the backup of VS's but it says where the MAR files are. Please refer the documentation at https://docops.ca.com/devtest-solutions/8-5/en/using/using-ca-service-virtualization/sv-installation-and-configuration.