if the target is a silver coin, the signal will likely show as silver when you swing over it from any direction. if it's a blob of rust and iron particles or even an old rusty nail, the signal will likely jump around when you swing over it from the different angles.
as for those one signal one way and another from another direction, well.... that could be a trashy target, it could be 2 different items side by side in the ground.
i generally run my 250 at 6 on the sensitivity. if i'm getting false signals from minerals, i'll lower the sens until the falsing stops. if i'm in a good clean, nail-free area, i'll even run it as high as 8. in really trashy places, down to 3. it all depends on where i am and what the actual ground conditions are like.
one thing you should be listening for are
consistent signals. i don't necessarily mean iron, lol. but anything else that stays consistent from any angle is something you should be digging.
one way signals can be a bit tricky. it's usually something trashy, but not always.
i took dug a one way signal that i was going to ignore and it turned out to be a 1927 nickle. the coin was on it's edge in the ground, it gave a one way signal and at 90 degrees, it didn't even show up on the detector. i pinpointed and dug it anyway and i wasn't disappointed.
Pete