Data Domain - When using failover bonding, standby interface has many dropped packets. This is expected since standby interface is not active.

net show config ethXx on standby interface shows a high number of dropped packets.

The standby interface is working as designed. 

Guidelines for configuring a bonded interface for failover
Link failover provides improved network stability and reliability by identifying backup interfaces that can support network traffic when the primary interface is not operating. These guidelines are provided to help you optimize your use of link failover.
● If a failover link has a defined primary interface, the primary interface removal results in an error message.
● If the primary interface goes down and multiple interfaces are still available, the next interface is randomly selected.
● All interfaces in a bonded interface must be on the same physical network. Network switches used by a bonded interface must be part of the same physical network.
● The recommended number of physical interfaces for failover is greater than one. You can, however, configure one 
interface.