Here is an example of a
UVSJ. It is a filter that accepts UHF signals on one port and VHF signals on another to combine into one coax. The UVSJ will have less loss than a two-way splitter connected in reverse and will prevent UHF signals received by the VHF antenna from interfering with the better quality UHF signals from the UHF antenna and vica versa.
I understand... if my wife is happy, I can be happy. If she's not happy, ain't nobody gonna be happy.
You may see a benefit to using an amplifier when splitting the signal. Amplifiers are not substitutes or fixes for antennas that are too small, the wrong type or installed incorrectly.
More on amplifiers