Interesting Protoss Sentry question

[StarCraft Poster]

Hi all,I have a question about the Sentry. As you know it has a shield for units under the shield that -2 damage from ranged attacks.if you have say 3 or 4 sentry next to each other all with there shields on over lapping each other does it make it 3 x -2 = -6 damage? or is it just one shield works.It doesn't stack, but obviously you can..

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