How to subscribe to multiple image topics using image_transport

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Hi,

I would like to subscribe multiple images using image_transport. Here is my code snapshot:

std::vecotr<std::string> topics = {"topicA", "topicB"};
mage_transport::ImageTransport it_(nh);
std::vector<image_transport::Subscriber> subs_;
for(size_t i = 0; i < topics.size(); i++) {
       subs_.push_back(it_->subscribe(topics[i], 1, &Process::ImageCallback, this)); 
}

When launching the node, I got the error: Tried to advertise a service that is already advertised in this node

Any suggestion is much appreciated. Thank you.

-----Update 20190604-------- This is a simplified code repo that reproduces the error: https://github.com/panda9095/example.