Value of Epsilon Decay Period

In the TF version of DQN, the value of `epsilon_decay_period` is set to 1M steps (see [here](https://github.com/google/dopamine/blob/a2753dae222c75ae991758d4110a84bc01c3215f/dopamine/agents/dqn/configs/dqn_nature.gin#L15)), and for Rainbow, the value is set to 250k steps (see [here](https://github.com/google/dopamine/blob/a2753dae222c75ae991758d4110a84bc01c3215f/dopamine/agents/rainbow/configs/rainbow.gin#L18)).

However, the [Rainbow paper](https://arxiv.org/pdf/1710.02298.pdf) says they anneal to 4M frames (i.e. 1M steps) for DQN (as done in Dopamine above), and _importantly_ without Noisy Nets (which is the case with TF Rainbow), they anneal in the first 250K _frames_ (and not steps, which would be 62500 steps with standard frame skipping of 4).

Is there a discrepancy here (Rainbow should anneal within 62k steps and not 250k steps), or am I misunderstanding something (or perhaps it really doesn't matter?). Thank you for your time.

Screenshot of page 4 of Rainbow paper