Some networks will maintain two active paths to and from the Internet. In addition to redundancy, these approaches can potentially double the available bandwidth, under normal conditions.
In most cases, the two paths are not designed to share traffic unless there is a failure. When all is well, a flow will be established on one of the paths, and all packets from that flow will traverse the same path.
In some cases, however, the network infrastructure is designed in such a way that cross both paths under normal circumstances. For example, inbound requests might come in on path A and outbound responses might go out on path B. Such traffic is said to be asymmetrically routed.
Of course, if one path becomes unavailable, all traffic will be routed across the remaining path.