How to create two Modern UI customisations on the same screen?

I have a customisation that adds a field to AP301000 - it’s part of a project that we’re deploying to pretty much all our customers.

I’ve another customisation that adds a very different set of fields to the same screen, and that will be deployed to a subset of our customers. (So it wouldn’t make sense to combine the projects at all.)

When I come to publish the second project, it fails with the error message:

The [published project] and  customization projects cannot be merged because they contain the duplicate AP301000 object.

The published typescript file has:

import {
  PXFieldState
} from "client-controls";
import {
  AP301000,
  APInvoice_CurrentDocument
} from "src/screens/AP/AP301000/AP301000";

export interface AP301000_PinnacleA_generated extends AP301000 {}

export class AP301000_PinnacleA_generated {}

export interface APInvoice_CurrentDocument_PinnacleA_generated
  extends APInvoice_CurrentDocument {}
export class APInvoice_CurrentDocument_PinnacleA_generated {
  UsrQueryReason: PXFieldState;
}
 

The (currently) unpublished file has:

import {  PXFieldState } from "client-controls";
import {
  AP301000,
  APInvoice_Document
} from "../AP301000";

export interface APInvoice_Document_PinnacleB
  extends APInvoice_Document {}
export class APInvoice_Document_PinnacleB {
  UsrCuryDeduction: PXFieldState;
}

What do I need to do to make these play nicely with each other??

Thanks!