This is not "imposition". When the official state language is already present, then what's the problem if additional languages are provided to help the local population?
Raichur may be geographically in Karnataka, but it is a border town (It is less than 15km from the border) and has had a significant Telugu population for a very long time, even from pre-independence times. A lot of the locals are also bilingual and speak both languages. This is the same case with most towns and cities that are close to state borders, in that they have different demographics compared to the interiors of the state. So these differences should be accounted for in these places.
So,...
more... kindly do not project these things as partiality or bias. For the record, Raichur has had multi-lingual SB's even before SCR or Andhra were created. Up until the 50's, Raichur didn't even have Kannada on the station board. The board used to be in Urdu, English, Tamil and Telugu. This was because Andhra was in the Madras Presidency at the time and Raichur was the interchange point for SR and CR. Later on, the Tamil name got dropped and was replaced with with Kannada and Hindi. The reason it still has Telugu now is not because of partiality or bias, rather something that already existed, being continued.
Another example for this is Vizianagaram (VZM) in AP, which is a good 50 km from the Orissa border (almost 100km by train/highways) and used to have the station board in English, Odiya, Telugu, Urdu and Hindi. Over time, Urdu and Odiya were removed from the boards as the demographics of the area changed.
Raichur, being a major place, has this kind of an arrangement. For many other small villages/towns and minor stations, language on the station boards is not a big issue.