I don't think it breaks anything horribly, but you would want to define what happens if one Aegis moves across another. Possibilities include:
- The moving Aegis compares its Penetration to the stationary Aegis' level and either penetrates or fizzles. (Probably current RAW.)
- Both Aegises compare Penetration and the lower one fizzles.
- Both Aegises remain in effect, as if they had successfully been cast separately on overlapping and/or concentric Boundaries; magi of either covenant will have a casting penalty within the area of overlap, unless they get an invite and casting token from their counterpart. (My preferred interpretation.)