it it possible to use the same alogorithm in two different publication?
Generally, yes.

It would be expected that there is some novel aspect in the second article, but the novel aspect does not need to be the algorithm.

It can be a different type of data (e.g., "bla algorithm applied to detect liver tumors" and "bla algorithm applied to detect stroke"), or a substantially larger dataset (e.g., "preliminary results of bla on 9 patients" and "results of bla on 500 patients"), etc.