You have MacProA, and MacProB. Let's say you want to share the screen on MacProB. In the latter System Preferences : Sharing, select Screen Sharing. Set your Allow access user setting, and under Computer Settings, set as appropriate. In System Preferences : Security & Privacy : Firewall Options… see if there is already an entry for Screen Sharing and Allow incoming connections is green. If not, you may need to press the + button to add it. I also have the following checked: Automatically allow signed software to receive incoming connections.
On MacProA, click on your Desktop, and then type shift+command+G to Go To Folder… and copy/paste the following into the text field of that dialog box:
/System/Library/CoreServices/Applications
This will open a Finder window on the Screen Sharing application location. Drag and drop it on your Dock. When you click on this Screen Sharing icon, it will prompt you with a Connect To dialog. Use the MacProB.local naming convention.