That's false. IBLT almost halves the bandwidth requirement. Currently transactions are sent twice: once when broadcast and once as part of a block when mined. IBLT reduces the bandwidth requirement of the latter to a constant.
That particular benefit is not attributable to IBLT.
You can stop sending transactions twice by putting transaction hashes, rather than full transactions, in the block message.
IBLT allows miners to broadcast (information that can be used to construct) those hashes while they mine rather than waiting after they found the block to send everything.