Yonks ago I wrote a post at AUGI lamenting the inability to repeat a column in a schedule. I shared my workaround which involved a second schedule showing just mark and then aligning the schedules, ouch!
Then the Revit team quietly enhanced schedules. Time passed and I never revisited the question. Well you CAN repeat a column, let's choose the Mark value for a door since that's what I wanted back then.
When you create a schedule you have the option to use the Calculated Value feature to create data. In this case we'll use it to make a second Mark parameter called "Mark2". Then we'll assign the data type: Text and then enter Mark for the formula which means it is equal to the Mark parameter already in our schedule.
Take a look at the image. The resulting little schedule in the upper left corner shows the second column and the other dialogs show how we got there.
Just make sure the data type of the Calculated Value is the same as the value you want to repeat.
Happy repeating columns!
(Note: This didn't become possible until Revit Building 9.0 was released)