Is there a module that provides a field for referencing values of another field Initially I thought I could use the same field on both entities, but I want the user to be able to select unlimited values from the reference field limited to the options that could exist in the original field.

In the field settings, I need to have the ability to select a field to reference.  When looking at the field instance I'd like to be able to tell which field the value should be compared against.  The user should be able to select from all of the possible values of field A and store that selection in field B.

Changed this, as it made it sound like I wanted something similar to node reference


  Entity 1: Field A 
  
  Entity 2: Field B (Values from Entity 1: Field A stored in Field B)


The goal is to be able to use Field B to find entities having Field A that are the same value

Is there any way to achieve this kind of relationship between fields?
Field reference module may help you !


  Defines a field type for referencing one field from another.
  
  This module is modelled on Node reference and usage is similar.
  
  Depending on configuration, authors can pick fields from the same
  node/entity, from other nodes/entities, from specific revisions, from
  specific languages, or even a specific delta value within the field.
  Fields can be displayed using either the 'full' or 'teaser' mode from
  their original node/entity.