can I add multiple ad units in one app?

[mxym]

can I add multiple ad units  in one app?

let's say in my app, there are 5 activities and I put different ad units on each activity.

e.g. 

activity 1 -> ad unit 1

activity 2 -> ad unit 2

activity 3 -> ad unit 3

activity 4 -> ad unit 4

activity 5 -> ad unit 5

will this violate the rules and getting banned?

OR  

same ad unit on all activities.

e.g.

activity 1 -> ad unit 1

activity 2 -> ad unit 1

activity 3 -> ad unit 1

activity 4 -> ad unit 1

activity 5 -> ad unit 1

will this violate the rules and getting banned?

[Shashidhar Yamsani]

You can safely use different ad unit Ids in each of the activities.