I'm basing this just off my observations. The strings that came on the guitar are darker, more of a subdued brown color, something I associate with phosphor bronze and are slicker to slide under the fingers. The masterbuilt 80/20 strings are a very bright yellow color and stickier. I could be completely wrong, but just from appearance and feel, the strings seem different.
I did buy the guitar from Sweetwater. Typically the guitars you get from them are factory fresh and not played previously. I'm also assuming they did not change the strings from the factory set.