Can I print invoice with multiple signature?

You can print invoices with multiple signature in BUSY but it would be done with user signature feature and you should have multiple users in BUSY so that invoice will be print with different signature and to enable it you need to follow some steps:
Step 1: Go to the administration and click on Users option.
Step 2: Now click on Add option and specify the user name.
Step 3: Now specify password and other details and click on Save option.
Step 4: Now Go to the Administration and then click on Configuration.
Step 5: Now click on feature and Options and then select the General Tab.
Step 6: Now enable the feature of Maintain Image and Signature with User and you can search it from F3 shortcut key.
Step 7: Now click on configure option and tick on Maintain signature image with User option.
Step 8: Now give the signature folder path where signature image exist in system and make sure image name should be from User name from which you login your company.
Step 9: Now click on OK option and save the General Tab.
Step 10: Now Go to the Administration and then click on Configuration.
Step 11: Now click on the Invoice Document Printing option and select the standard option.
Step 12: Now select the invoice type in which you want to print signature and enable the option of Print User Signture or search it from F3 shortcut key.
Step 13: Now save the standard configuration and Go to the Transaction.
Step 14: Now select the voucher type and select modify option.
Step 15: Now enter the invoice number and click on ok option 
Step 16: Now click print option and select the Sale invoice option.
Step 17: Now select the Standard format and click on print.