Keyholes, IGS 1B and the USA 144 decoy
The latter object is an interesting one. It was part of the launch of what is believed to be the second stealth reconnaissance satellite, Misty-2. After being picked up by amateur observers and observed for some time, doubts began to grow whether it really was the main payload. Ted Molczan determined from the obital evolution that the object did not appear dense enough to be an operational satellite (i.e. USA 144 itself), something further suggested by the fact that it appeared to be slowly tumbling. Instead, it is either a weird piece of debris from the Delta IV used to launch USA 144; or a deliberate decoy used to get attention away from the real payload. See here, here and here for the details.
Below are one of the images of the USA 144 Decoy which I obtained yesterday evening (it is crossing the northwest corner of Pegasus here), it's orbit, and the launch patch of the 1999 launch.
The object was almost 10 seconds early relative to a 17-day old elset. It shows a slow but clear brightness variation over the image series.
The KH-12 Keyhole USA 186 (05-042A) was 2 seconds early relative to an elset of the previous day. USA 129 (96-072A) was on-time. IGS 1B (03-009B) was 0.25s late.