To the best of my knowledge, this was an accusation made by Kasparov after he lost the game, there is no actual evidence of this happening - or if it was within the rules of the tournament (to tweak). As you might know, "Deep Blue" was more than just software, a big part of deep blue was its massive parallel processing power crunching literally 200 million nodes per second (nps or positions per second), even though source code of deep blue is not available to public, raw logs of the game are available and nothing from those logs suggest that any monkey business was going on (it has been debunked many times).
I think Kasparov got overwhelmed by the numbers that DB was crunching and he lost the game psychologically even before the game started. If you actually studied the games he played against DB - you would see amateur mistakes made by one of the world's greatest grandmaster.
I think if he knew he wasn't playing a computer, he could have done a lot better.
Regardless, there is no comparison between deep blue and modern computer engines. To the best of my knowledge, most (popular) comp-comp tournaments and comp-human tournament, the binaries of the engines are given to the tournament organizers which are used in all games throughout the tournament. This is most definitely true for comp-human games; for comp-comp games it might depend on the participants and the organization hosting the tournament.
Kasparov lost the last and deciding game of the match with a horrible blunder playing the Caro-Kann, a defence he did not often play.
Kasparov believed that the Deep Blue team had spent a lot of time analyzing his style and looking for weaknesses. He felt it was unfair that Deep Blue was designed to beat him, personally, but he wasn't able to study it in the same way.
Kasparov decided to play an unusual defence in game 6 hoping to avoid any theoretical surprises his opponents may have prepared against his favourite defences, but it didn't work. At the same time, the pressure he was under no doubt contributed to his defeat.
Of course now Rybka doesn't need any 'help' from human handlers, it can comfortably beat strong Grandmasters (Rybka 3's ELO is over 3200).
If it is any consolation the surge in computer chess strength is largely thought to be due to modern engines evaluating positions more like a human would, rather than looking at more positions.
I think Kasparov got overwhelmed by the numbers that DB was crunching and he lost the game psychologically even before the game started. If you actually studied the games he played against DB - you would see amateur mistakes made by one of the world's greatest grandmaster.
I think if he knew he wasn't playing a computer, he could have done a lot better.
Regardless, there is no comparison between deep blue and modern computer engines. To the best of my knowledge, most (popular) comp-comp tournaments and comp-human tournament, the binaries of the engines are given to the tournament organizers which are used in all games throughout the tournament. This is most definitely true for comp-human games; for comp-comp games it might depend on the participants and the organization hosting the tournament.