Musannaf Ibn Abi Shaybah

It is narrated from Ibrahim that if a person in the state of Ihram needs to wear a shirt, or to have his head shaved, or to do any other such act which is not appropriate for us to do, then if he does all of them together, only one sacrifice (dam) is required of him; but if he does each act separately, then a separate sacrifice (dam) will be required for each act.

Hasan and Hazrat Ata say that if he performs all the acts together, then only one sacrifice (dam) is obligatory upon him, and if he performs them at separate times, then a sacrifice (dam) is obligatory for each one.