IOS7 - How do I sync outlook contacts from two mail accounts?

For an iPhone 5, running ios7:

I have a personal computer, with Outlook and personal contacts that I routinely sync to using the USB cable and iTunes.

I also have a business Outlook Exchange e-mail account that I have added to the phone for e-mail and calendar functions.

so far, so good.

The problem: When I go to turn on the contacts from the Outlook Exchange e-mail account, the message asks me if I want to overwrite the contacts on the phone or keep them.

For comparison: The calendar from my personal computer simply shows up as a separate calendar from the Outlook Exchange e-mail account. I can select to show them individually, or together. The calendar from the Outlook Exchange e-mail account syncs automatically with the account - any changes I make on the phone go back to the server and show up on my work computer.

I want both sets of contacts on the phone, but not combined. I want to be able to keep my personal contacts (synched on my computer) completely separate from the Outlook Exchange e-mail account contacts (similar to the calendar). My concern is that the contacts will get combined and I have to sort them back out again. (I have over a thousand contacts - too many to sort out)

Is there any way to put both sets of contacts on the iphone, but keep them separate?