Conflicting kerning not shown when compiling

I am doing the spacing and kerning on a font family. After checking as good as possible, I compiled the fonts (Font Info) to be sure everything was in order. No errors.

When I exported the fonts as UFO and send them to my client, they reported a problem of double kerned glyphs, after checking the kerning with Metrics Machine. Apparently I made some double kerning exceptions which overlapped. A pair (/icircumflex/icircumflex) had two kerning values for example.
– First, I didn’t think it would be possible, even in G2…
– Second, is there a way to find similar errors in G2 ? I didn’t find it and the KERN feature is written after exporting/generating fonts.

Can you send the font (remove all outlines of needed).