From my memory, cable splitters (such as for splitting a cable tv coax cable into two televisions) provide impedance matching to prevent signal reflections, etc.
If one 50 Ohm line is split into two 50 Ohm lines, the two will appear as a single 25 Ohm line (two 50 Ohm lines in parallel). The splitter, therefor, will include 25 Ohm impedance in series with the incoming line. Half the incoming power is dissapated in this impedance and the other half is split between the two cables, so there is -6dB loss on each line.
Yet... recently looking at splitters I've noticed some for sale advertising -3.5 dB attenuation on each line.
How is this possible without impedance matching issues?