It is also helpful to say that you will be travelling to a country that does not accept passports with entrance stamps from certain countries: such as, Saudi Arabia and Syria who do not let people enter the country if you have visited Israel. I will share an example letter at my company that we use to aid staff to get a second Passport:-
UK PASSPORT OFFICE
Second Passport Application
This is to confirm that xxx is employed by this company as xxx. He/she has been in our employ since [date].
[Name] is a frequent traveller and is therefore in need of a second passport as we anticipate several trips over the company months. Several countries that [he/she] will be travelling to will require visas and therefore we would request a second passport to expedite these while [he/she] is traveling.
Over the coming months and into next year, [he/she] might be required to travel to:
Nigeria – September 2010
China – October 2010
Russian Federation – November 2010
Saudi Arabia – January 2010
Pakistan – January 2010
India – January 2010
Israel – February 2010
We confirm that [he/she] will return to the United Kingdom to resume employment with this company after this trip. Please assist [he/she] in obtaining a passport allowing her to enter travel.
If you require any further information with regards to [he/she] employment with this company, please do not hesitate to contact me on the above number.