I'm fairly sure what you want to do is called NIC/Interface bonding, a.k.a. NIC teaming.
This will allow two (or more) NIC's to appear as a single NIC. This does assume that your blade chassis does have either two switches or two pass through NIC modules so that the two NIC's on the blade server both have physical paths into the network.
https://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/ref-guide/s1-networkscripts-interfaces.html#S2-NETWORKSCRIPTS-INTERFACES-CHAN