Sure, but in most cases it's probably not worth the effort. If all you need is something super simple, you might save a few bucks by getting 2 separate policies. But as soon as you start tweaking things you may find the savings dwindle.
Let's say you buy home and contents policies and add flood cover to each. You're already talking 4 products. You're more likely to get a discount on all that with 1 company than if you split the purchases. Not to mention the time saved on paperwork.
By all means search around for the best deals, but be aware of the hidden costs in both money and time.