Throughout your life you may find that your need for life insurance has changed.
For example, if you have a major life event happen, such as, get married, have a child, get a promotion, buy your first home, you may find you have an increased need for more life insurance.
In addition, you may be provided life insurance coverage through your employer, this is called a group term life insurance plan that covers all employees in the plan.
However, you still can buy your own separate life insurance policy outside of your employment. And, you may own more than 1 life insurance policy depending on your needs.
When you apply for life insurance the application asks if you have any other life insurance policies, and how much total life insurance coverage you own.
They ask this question so you aren't over-insured. But, most life insurance carriers will allow you to own up to 10-20 times your income in life insurance.
So, if you earn $50,000 a year, you may qualify for up to $1,000,000 or more of life insurance protection.
Here's an article with more information on How many life insurance policies can you have?