MinHash Locality Sensitive Hashing (LSH) was used to find and remove near-duplicates from large chemical datasets to avoid data leakage during training and testing of AI models for forward prediction modelling. The MinHash LSH algorithm is a nearest-neighbour algorithm which provides query times in O(n) time complexity, while pairwise comparisons require O(n²) time complexity, making them intractable for large datasets. A recent attention neural network, Molecular Transformer, was tested on the combination of three large datasets with and without the removal of these near-duplicates and compared against literature. It was concluded that MinHash LSH provides an elegant approach to removing near-duplicates. Furthermore, the reported results of the Molecular Transformer where not generalizable to aggregated datasets, although the reduced accuracy of the model on a reduced dataset could be shown.