The first PAX demo of Bendy and the Ink Machine was a demo for Chapter 2: The Old Song that was released at PAX West/East around April 2017, before the full chapter's release as a DLC on April 18, 2017. The chapter itself was very different at the time, with different enemy models, some shorter objectives, etc.
You can download this and other old versions here.
The Searchers' model was completely different from their final design. Each hand possesses three fingers instead of five, with two longer ones closely resembling a tuning fork. Their arms seem to also be thinner than the new model. Their face also seems to be painted partly with grayish-white colors (yellowish-brown due to the game's lighting). They appear to be slightly shorter than Henry. Instead of crawling, they just move in a similar fashion to a slug's movement while swaying their arms. They collapse into pieces whenever they damaged Henry, or even simply running into obstacles or walls.
Sammy's appearance is completely different from his final version. His body structure is slender and has more inhuman-looking skin texture. His overalls are fairly different, looking bigger and slightly looser. His shoes and the lower parts of his overalls are melted into ink, appearing to be made out of sticky glue while he walks. While his mask look identical, it has a duplicated texture from the back while the hole from the mask's mouth is bigger.
Beta
Final
Sammy's animation during his monologue is simply him standing idle unlike the final version which is more various and moving. He doesn't have any dustpan in his hand when he knocks out Henry.
Ink Bendy's beta model is similar to his final version but with less details. The horns of Ink Bendy do not move due to lack of modeling bones and he entirely lacks the ability to cause ink spreading on areas from his surroundings. His chase segment was far shorter.
