I don't believe it is the same, the spec says 0.5dB of insertion loss.
.5dB is the insertion loss above the mathematical 3dB loss of a two-way split/combine. All passive RF circuits/devices have two loss specifications; that of the mathematical power/energy loss per branch (2-way split = 3dB per branch; 4-way = 6dB per branch; 8-way = 9dB per branch . . .), and the physical insertion loss due to real-world physics of no transmission line being lossless.
Wilkinson circuits are the most commonly available splitter/combiner circuits and typically have .5-1dB insertion loss (above the mathematical loss) based on frequency range, power handling and connection type. The other important parameter, especially when using this circuit for combining, is port to port isolation; the greater the better, so as to feed as little power as possible from one transmitter into the other. (Isolators are generally recommended in between the TX port and the combiner port, but they are very expensive are not truly needed in this particularl low power 2-way application.)
A 3+dB loss on the inbound (RX) side is not a major concern. On the outbound (TX) side, it can be since the absolute loss is greater. Ensure the link budget permits the loss at the RF power output level available.
