combining trained neural nets in tensorflow
It seems merging two neural networks does not make any sense. You may instead train one deep R-CNN or with just 2 different NN trained, You may classify as for a test case,if outputs of both NN agree, then output the common output, else the NN which outputs 1, its precision and NN which outputs -1, ratio of its correct negatives to total cases which it predicted negative(calculated in training), whichever is greater, output that NN's output.
Hope these articles will help you.
Build Your First Deep Learning Classifier using TensorFlow: Dog Breed Example
Deep Learning Part 3: Combining Deep Convolutional Neural Network with Recurrent Neural Network