Some Walmart delivery drivers bringing groceries to customers' homes aren't who they say they are

• Walmart's delivery platform, Spark, has tripled its delivery-driver workforce over the past year.
• But employees and drivers say the platform has an issue with drivers posing under multiple names.
• Walmart is rolling out a facial-recognition and ID-scan system to verify identities and prevent fraud.

When Mike Del Rio began delivering orders for Walmart's in-house delivery platform, Spark, about a year ago, the money was good.