Please use Post A Answer to post follow up questions. Starting a new thread means that your readers don't see what went before and this can force you to reexplain a lot about your solution.
The only way to have two layouts open is to open two windows, one for each layout.
But you can also set up a portal in a form view layout listing your client info and then fields showing the details of that client could be placed next to the portal. A button in the portal row can perform a script that finds the record using a scripted find or Go To Related record to display the detail info.