What the 4/0 driver count means for your BOM
The 4/0 driver/receiver split is the first fit check: this part drives four differential pairs but does not include a single receiver. If your design needs bidirectional RS485 communication, you must add an external receiver IC. For pure transmit-only applications — broadcasting data from a controller to multiple remote nodes — the 4/0 count is exactly what you want, saving the cost and board area of unused receiver channels.
No official second-source alternate is listed on this record, so dual-sourcing would require a pin-compatible evaluation against a different vendor's quad RS485 driver.