Issues with loading from RXN file after saving to RXN several reactions positioned one under the another

**Steps to Reproduce Scenario 1**
1. Add to Canvas two reactions with Benzene Rings:
2. Click on Save as...
3. Click on Warnings and observe

**Actual Behavior**
Wrong warning is displayed: "The MDL Rxnfile V2000 format does not support drawn elements: reaction arrows will be lost:

**Expected behavior**
TBD - for example: Multistep reactions cannot be saved to this format. Only the first step will be saved

4. Check RXN preview and copy:

**Actual Behavior**
Reactants from two reactions are together on the left side, products from two reactions are together on the right side:

**Expected behavior**
Only the first reaction should be in RXN, it should be 2:1

5. Paste to Canvas and observe

**Actual behavior**
Reactions are corrupted, and additional pluses are added:

**Expected behavior**
TBD - Only one first reaction is pasted

**Environment details:**
- Ketcher version: [Version 2.23.0-rc.3] Build at 2024-07-14; 20:34:10
- Indigo version: Version 1.22.0-rc.3.0-gbb5c51fc2-wasm32-wasm-clang-19.0.0

**Additional context**
- Detected during investigation of RDF feature - https://github.com/epam/Indigo/issues/2030.