There are two factors contributing to this, as you say, glare: (1) That's how omnidirectional light sources work IRL; they cast brighter and more direct light on surfaces closest to them. Source has a very realistic lighting model and expects you to play along by making your light sources as true to life as possible, for the most part. (2) You probably compiled with HDR enabled, and by default, HDR has very extreme exposure limits that amplify contrasts in lighting levels.
If your map is in the early testing phases and you're just placing lights for the sake of not being too dark to play in, I wouldn't worry too much about #1 and would recommend remedying #2 by just compiling without HDR for now. Eventually, you'll want to replace them with more normal light sources, mostly light_spot entities, which only cast light in one direction, usually down. This will get rid of your problem permanently. Omnidirectional light is only used on very rare occasions in Source games, for things like bare light bulbs or candles.
If your map is in the early testing phases and you're just placing lights for the sake of not being too dark to play in, I wouldn't worry too much about #1 and would recommend remedying #2 by just compiling without HDR for now. Eventually, you'll want to replace them with more normal light sources, mostly light_spot entities, which only cast light in one direction, usually down. This will get rid of your problem permanently. Omnidirectional light is only used on very rare occasions in Source games, for things like bare light bulbs or candles.