The full text of the "blue box" at the end of <R1> reads as follows, with a portion bolded for emphasis:
The intent of <R1a>, <R1b>, and <R1c> are to ensure an unambiguous level playing field for all Teams. Teams are welcome (and encouraged) to improve or modify their Robots between events, or to collaborate with other Teams to develop the best possible game solution.
However, a Team who brings and / or competes with two separate Robots at the same tournament has diminished the efforts of a Team who spent extra design time making sure that their one Robot can accomplish all of the game’s tasks. Similarly, a multi-team organization that shares a single Robot has diminished the efforts of a multi-team organization who puts in the time, effort, and resources to undergo separate individual design processes and develop their own Robots.
To help determine if a robot is a “separate Robot” or not, use the Subsystem definitions found in <R1>. Above that, use common sense as referenced in <G3>. If you can place two complete and legal Robots on a table next to each other, then they are two separate Robots. Trying to decide if changing a pin, a wheel, or a motor constitutes a separate Robot is missing the intent and spirit of this rule.
Most Robot rules, including <R1>, are intended to apply within the context of a competition event. For example, <R1-a> is intended to prohibit competing with one Robot in a Match while a second Robot is being assembled in the Team pit area.
There are no rules prohibiting the use of a separate "practice Robot" between events, provided that no other rules are violated (namely, <R1-c>, <R2>, <G2>, etc).